diff --git a/.eslintrc.js b/.eslintrc.js
index b34ffcf694..40dfd21433 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = {
   extends: ['plugin:eslint-comments/recommended', 'standard', 'standard-jsx', 'prettier'],
   globals: {
@@ -45,5 +47,7 @@ module.exports = {
     'lines-between-class-members': 'off',
 
     'no-console': ['error', { allow: ['warn', 'error'] }],
+
+    strict: 'error',
   },
 }
diff --git a/@vates/coalesce-calls/index.js b/@vates/coalesce-calls/index.js
index 7999fe76d0..1dfa729cb4 100644
--- a/@vates/coalesce-calls/index.js
+++ b/@vates/coalesce-calls/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.coalesceCalls = function (fn) {
   let promise
   const clean = () => {
diff --git a/@vates/coalesce-calls/index.spec.js b/@vates/coalesce-calls/index.spec.js
index 7bc9d8e076..1fe505d7d2 100644
--- a/@vates/coalesce-calls/index.spec.js
+++ b/@vates/coalesce-calls/index.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { coalesceCalls } = require('./')
diff --git a/@vates/compose/index.spec.js b/@vates/compose/index.spec.js
index 82b7baab8a..8425c5f32b 100644
--- a/@vates/compose/index.spec.js
+++ b/@vates/compose/index.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { compose } = require('./')
diff --git a/@vates/decorate-with/index.js b/@vates/decorate-with/index.js
index 9c40038661..2b7d1153bf 100644
--- a/@vates/decorate-with/index.js
+++ b/@vates/decorate-with/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.decorateWith = function decorateWith(fn, ...args) {
   return (target, name, descriptor) => ({
     ...descriptor,
diff --git a/@vates/disposable/debounceResource.js b/@vates/disposable/debounceResource.js
index f626a9a797..1200527f07 100644
--- a/@vates/disposable/debounceResource.js
+++ b/@vates/disposable/debounceResource.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap } = require('@xen-orchestra/async-map')
 const { createLogger } = require('@xen-orchestra/log')
 
diff --git a/@vates/disposable/debounceResource.spec.js b/@vates/disposable/debounceResource.spec.js
index 4033ac8056..c342979f58 100644
--- a/@vates/disposable/debounceResource.spec.js
+++ b/@vates/disposable/debounceResource.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { createDebounceResource } = require('./debounceResource')
diff --git a/@vates/disposable/deduped.js b/@vates/disposable/deduped.js
index 87a0a4f84a..d5879ba89d 100644
--- a/@vates/disposable/deduped.js
+++ b/@vates/disposable/deduped.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const ensureArray = require('ensure-array')
 const { MultiKeyMap } = require('@vates/multi-key-map')
 
diff --git a/@vates/disposable/deduped.spec.js b/@vates/disposable/deduped.spec.js
index 96521798d3..38f43946df 100644
--- a/@vates/disposable/deduped.spec.js
+++ b/@vates/disposable/deduped.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { deduped } = require('./deduped')
diff --git a/@vates/multi-key-map/index.js b/@vates/multi-key-map/index.js
index e3f74f2ca7..aa4707b96d 100644
--- a/@vates/multi-key-map/index.js
+++ b/@vates/multi-key-map/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 class Node {
   constructor(value) {
     this.children = new Map()
diff --git a/@vates/multi-key-map/index.spec.js b/@vates/multi-key-map/index.spec.js
index ae1c46d1d5..cfc94f2813 100644
--- a/@vates/multi-key-map/index.spec.js
+++ b/@vates/multi-key-map/index.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { MultiKeyMap } = require('./')
diff --git a/@vates/parse-duration/index.js b/@vates/parse-duration/index.js
index c026343ba8..66783a9def 100644
--- a/@vates/parse-duration/index.js
+++ b/@vates/parse-duration/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const ms = require('ms')
 
 exports.parseDuration = value => {
diff --git a/@vates/read-chunk/index.js b/@vates/read-chunk/index.js
index d90166b14c..d73633c4c9 100644
--- a/@vates/read-chunk/index.js
+++ b/@vates/read-chunk/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const readChunk = (stream, size) =>
   size === 0
     ? Promise.resolve(Buffer.alloc(0))
diff --git a/@vates/read-chunk/index.spec.js b/@vates/read-chunk/index.spec.js
index f94faf3134..83aeee77df 100644
--- a/@vates/read-chunk/index.spec.js
+++ b/@vates/read-chunk/index.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { Readable } = require('stream')
diff --git a/@vates/toggle-scripts/index.js b/@vates/toggle-scripts/index.js
index a9e2606855..872f292a43 100755
--- a/@vates/toggle-scripts/index.js
+++ b/@vates/toggle-scripts/index.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+'use strict'
+
 const fs = require('fs')
 
 const mapKeys = (object, iteratee) => {
diff --git a/@xen-orchestra/async-map/index.js b/@xen-orchestra/async-map/index.js
index 2e50801568..f25de2f97a 100644
--- a/@xen-orchestra/async-map/index.js
+++ b/@xen-orchestra/async-map/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const wrapCall = (fn, arg, thisArg) => {
   try {
     return Promise.resolve(fn.call(thisArg, arg))
diff --git a/@xen-orchestra/async-map/index.spec.js b/@xen-orchestra/async-map/index.spec.js
index e1262924c5..3392d5f50b 100644
--- a/@xen-orchestra/async-map/index.spec.js
+++ b/@xen-orchestra/async-map/index.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { asyncMapSettled } = require('./')
diff --git a/@xen-orchestra/async-map/legacy.js b/@xen-orchestra/async-map/legacy.js
index 584c9c6982..260900a012 100644
--- a/@xen-orchestra/async-map/legacy.js
+++ b/@xen-orchestra/async-map/legacy.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // type MaybePromise<T> = Promise<T> | T
 //
 // declare export function asyncMap<T1, T2>(
diff --git a/@xen-orchestra/audit-core/.babelrc.js b/@xen-orchestra/audit-core/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/audit-core/.babelrc.js
+++ b/@xen-orchestra/audit-core/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/backups-cli/_composeCommands.js b/@xen-orchestra/backups-cli/_composeCommands.js
index a2d899e95b..cd6480c804 100644
--- a/@xen-orchestra/backups-cli/_composeCommands.js
+++ b/@xen-orchestra/backups-cli/_composeCommands.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const getopts = require('getopts')
 
 const { version } = require('./package.json')
diff --git a/@xen-orchestra/backups-cli/_fs.js b/@xen-orchestra/backups-cli/_fs.js
index cebc573b93..d053c1899c 100644
--- a/@xen-orchestra/backups-cli/_fs.js
+++ b/@xen-orchestra/backups-cli/_fs.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { dirname } = require('path')
 
 const fs = require('promise-toolbox/promisifyAll')(require('fs'))
diff --git a/@xen-orchestra/backups-cli/commands/clean-vms.js b/@xen-orchestra/backups-cli/commands/clean-vms.js
index 863891ecef..d02bc471fe 100644
--- a/@xen-orchestra/backups-cli/commands/clean-vms.js
+++ b/@xen-orchestra/backups-cli/commands/clean-vms.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+'use strict'
+
 // -----------------------------------------------------------------------------
 
 const asyncMap = require('lodash/curryRight')(require('@xen-orchestra/async-map').asyncMap)
diff --git a/@xen-orchestra/backups-cli/commands/create-symlink-index.js b/@xen-orchestra/backups-cli/commands/create-symlink-index.js
index 82deb56c9f..b9030ca421 100644
--- a/@xen-orchestra/backups-cli/commands/create-symlink-index.js
+++ b/@xen-orchestra/backups-cli/commands/create-symlink-index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const filenamify = require('filenamify')
 const get = require('lodash/get')
 const { asyncMap } = require('@xen-orchestra/async-map')
diff --git a/@xen-orchestra/backups-cli/commands/info.js b/@xen-orchestra/backups-cli/commands/info.js
index 38d6d727d8..1ec157e82d 100644
--- a/@xen-orchestra/backups-cli/commands/info.js
+++ b/@xen-orchestra/backups-cli/commands/info.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const groupBy = require('lodash/groupBy')
 const { asyncMap } = require('@xen-orchestra/async-map')
 const { createHash } = require('crypto')
diff --git a/@xen-orchestra/backups-cli/index.js b/@xen-orchestra/backups-cli/index.js
index 2f12430df4..45e02c435d 100755
--- a/@xen-orchestra/backups-cli/index.js
+++ b/@xen-orchestra/backups-cli/index.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+'use strict'
+
 require('./_composeCommands')({
   'clean-vms': {
     get main() {
diff --git a/@xen-orchestra/backups/Backup.js b/@xen-orchestra/backups/Backup.js
index 67a5cffc8d..0cac583942 100644
--- a/@xen-orchestra/backups/Backup.js
+++ b/@xen-orchestra/backups/Backup.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap, asyncMapSettled } = require('@xen-orchestra/async-map')
 const Disposable = require('promise-toolbox/Disposable')
 const ignoreErrors = require('promise-toolbox/ignoreErrors')
diff --git a/@xen-orchestra/backups/DurablePartition.js b/@xen-orchestra/backups/DurablePartition.js
index c4ed0069a9..bbf68526c1 100644
--- a/@xen-orchestra/backups/DurablePartition.js
+++ b/@xen-orchestra/backups/DurablePartition.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap } = require('@xen-orchestra/async-map')
 
 exports.DurablePartition = class DurablePartition {
diff --git a/@xen-orchestra/backups/ImportVmBackup.js b/@xen-orchestra/backups/ImportVmBackup.js
index 1b71fce31d..a4cf569701 100644
--- a/@xen-orchestra/backups/ImportVmBackup.js
+++ b/@xen-orchestra/backups/ImportVmBackup.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 
 const { formatFilenameDate } = require('./_filenameDate.js')
diff --git a/@xen-orchestra/backups/RemoteAdapter.js b/@xen-orchestra/backups/RemoteAdapter.js
index 19fc131016..7ae0d95a77 100644
--- a/@xen-orchestra/backups/RemoteAdapter.js
+++ b/@xen-orchestra/backups/RemoteAdapter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap, asyncMapSettled } = require('@xen-orchestra/async-map')
 const Disposable = require('promise-toolbox/Disposable')
 const fromCallback = require('promise-toolbox/fromCallback')
diff --git a/@xen-orchestra/backups/RestoreMetadataBackup.js b/@xen-orchestra/backups/RestoreMetadataBackup.js
index 822d4ff4db..0bc2214565 100644
--- a/@xen-orchestra/backups/RestoreMetadataBackup.js
+++ b/@xen-orchestra/backups/RestoreMetadataBackup.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { DIR_XO_POOL_METADATA_BACKUPS } = require('./RemoteAdapter.js')
 const { PATH_DB_DUMP } = require('./_PoolMetadataBackup.js')
 
diff --git a/@xen-orchestra/backups/Task.js b/@xen-orchestra/backups/Task.js
index b491b4a811..554b20ec87 100644
--- a/@xen-orchestra/backups/Task.js
+++ b/@xen-orchestra/backups/Task.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const CancelToken = require('promise-toolbox/CancelToken')
 const Zone = require('node-zone')
 
diff --git a/@xen-orchestra/backups/_PoolMetadataBackup.js b/@xen-orchestra/backups/_PoolMetadataBackup.js
index 1a54afbd29..3eedff98b3 100644
--- a/@xen-orchestra/backups/_PoolMetadataBackup.js
+++ b/@xen-orchestra/backups/_PoolMetadataBackup.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap } = require('@xen-orchestra/async-map')
 
 const { DIR_XO_POOL_METADATA_BACKUPS } = require('./RemoteAdapter.js')
diff --git a/@xen-orchestra/backups/_VmBackup.js b/@xen-orchestra/backups/_VmBackup.js
index 8510fd5e02..4c0284d8d4 100644
--- a/@xen-orchestra/backups/_VmBackup.js
+++ b/@xen-orchestra/backups/_VmBackup.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const findLast = require('lodash/findLast.js')
 const groupBy = require('lodash/groupBy.js')
diff --git a/@xen-orchestra/backups/_XoMetadataBackup.js b/@xen-orchestra/backups/_XoMetadataBackup.js
index bacc3a3fd3..7171978f3d 100644
--- a/@xen-orchestra/backups/_XoMetadataBackup.js
+++ b/@xen-orchestra/backups/_XoMetadataBackup.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap } = require('@xen-orchestra/async-map')
 
 const { DIR_XO_CONFIG_BACKUPS } = require('./RemoteAdapter.js')
diff --git a/@xen-orchestra/backups/_backupType.js b/@xen-orchestra/backups/_backupType.js
index 7e41a5d665..2ab79a2c94 100644
--- a/@xen-orchestra/backups/_backupType.js
+++ b/@xen-orchestra/backups/_backupType.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.isMetadataFile = filename => filename.endsWith('.json')
 exports.isVhdFile = filename => filename.endsWith('.vhd')
 exports.isXvaFile = filename => filename.endsWith('.xva')
diff --git a/@xen-orchestra/backups/_backupWorker.js b/@xen-orchestra/backups/_backupWorker.js
index 248b5f0eb4..adf1edc823 100644
--- a/@xen-orchestra/backups/_backupWorker.js
+++ b/@xen-orchestra/backups/_backupWorker.js
@@ -1,3 +1,5 @@
+'use strict'
+
 require('@xen-orchestra/log/configure.js').catchGlobalErrors(
   require('@xen-orchestra/log').createLogger('xo:backups:worker')
 )
diff --git a/@xen-orchestra/backups/_cancelableMap.js b/@xen-orchestra/backups/_cancelableMap.js
index e58509c759..b7c085260e 100644
--- a/@xen-orchestra/backups/_cancelableMap.js
+++ b/@xen-orchestra/backups/_cancelableMap.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const cancelable = require('promise-toolbox/cancelable')
 const CancelToken = require('promise-toolbox/CancelToken')
 
diff --git a/@xen-orchestra/backups/_cleanVm.integ.spec.js b/@xen-orchestra/backups/_cleanVm.integ.spec.js
index efb972c798..f9944e1868 100644
--- a/@xen-orchestra/backups/_cleanVm.integ.spec.js
+++ b/@xen-orchestra/backups/_cleanVm.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const rimraf = require('rimraf')
diff --git a/@xen-orchestra/backups/_cleanVm.js b/@xen-orchestra/backups/_cleanVm.js
index bc8c9c4e38..8e044675a7 100644
--- a/@xen-orchestra/backups/_cleanVm.js
+++ b/@xen-orchestra/backups/_cleanVm.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const sum = require('lodash/sum')
 const { asyncMap } = require('@xen-orchestra/async-map')
diff --git a/@xen-orchestra/backups/_deltaVm.js b/@xen-orchestra/backups/_deltaVm.js
index b5b2b5a364..7d1b74cf83 100644
--- a/@xen-orchestra/backups/_deltaVm.js
+++ b/@xen-orchestra/backups/_deltaVm.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const compareVersions = require('compare-versions')
 const find = require('lodash/find.js')
 const groupBy = require('lodash/groupBy.js')
diff --git a/@xen-orchestra/backups/_extractIdsFromSimplePattern.js b/@xen-orchestra/backups/_extractIdsFromSimplePattern.js
index 237752d571..3620c7c2d0 100644
--- a/@xen-orchestra/backups/_extractIdsFromSimplePattern.js
+++ b/@xen-orchestra/backups/_extractIdsFromSimplePattern.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.extractIdsFromSimplePattern = function extractIdsFromSimplePattern(pattern) {
   if (pattern === undefined) {
     return []
diff --git a/@xen-orchestra/backups/_filenameDate.js b/@xen-orchestra/backups/_filenameDate.js
index 6eb4aebed8..0e6441a48f 100644
--- a/@xen-orchestra/backups/_filenameDate.js
+++ b/@xen-orchestra/backups/_filenameDate.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { utcFormat, utcParse } = require('d3-time-format')
 
 // Format a date in ISO 8601 in a safe way to be used in filenames
diff --git a/@xen-orchestra/backups/_forkStreamUnpipe.js b/@xen-orchestra/backups/_forkStreamUnpipe.js
index 72de36795a..c3acb85010 100644
--- a/@xen-orchestra/backups/_forkStreamUnpipe.js
+++ b/@xen-orchestra/backups/_forkStreamUnpipe.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const eos = require('end-of-stream')
 const { PassThrough } = require('stream')
 
diff --git a/@xen-orchestra/backups/_getOldEntries.js b/@xen-orchestra/backups/_getOldEntries.js
index 9313abf6dc..3e450b72c6 100644
--- a/@xen-orchestra/backups/_getOldEntries.js
+++ b/@xen-orchestra/backups/_getOldEntries.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // returns all entries but the last retention-th
 exports.getOldEntries = function getOldEntries(retention, entries) {
   return entries === undefined ? [] : retention > 0 ? entries.slice(0, -retention) : entries
diff --git a/@xen-orchestra/backups/_getTmpDir.js b/@xen-orchestra/backups/_getTmpDir.js
index a96f5d00a4..aa9225f296 100644
--- a/@xen-orchestra/backups/_getTmpDir.js
+++ b/@xen-orchestra/backups/_getTmpDir.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const Disposable = require('promise-toolbox/Disposable')
 const { join } = require('path')
 const { mkdir, rmdir } = require('fs-extra')
diff --git a/@xen-orchestra/backups/_getVmBackupDir.js b/@xen-orchestra/backups/_getVmBackupDir.js
index 0e001c6055..30ae90bf93 100644
--- a/@xen-orchestra/backups/_getVmBackupDir.js
+++ b/@xen-orchestra/backups/_getVmBackupDir.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const BACKUP_DIR = 'xo-vm-backups'
 exports.BACKUP_DIR = BACKUP_DIR
 
diff --git a/@xen-orchestra/backups/_isValidXva.js b/@xen-orchestra/backups/_isValidXva.js
index 0ec7d7df3c..c89a4406cf 100644
--- a/@xen-orchestra/backups/_isValidXva.js
+++ b/@xen-orchestra/backups/_isValidXva.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 
 const COMPRESSED_MAGIC_NUMBERS = [
diff --git a/@xen-orchestra/backups/_listPartitions.js b/@xen-orchestra/backups/_listPartitions.js
index e3ac803923..62f718b047 100644
--- a/@xen-orchestra/backups/_listPartitions.js
+++ b/@xen-orchestra/backups/_listPartitions.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const fromCallback = require('promise-toolbox/fromCallback')
 const { createLogger } = require('@xen-orchestra/log')
 const { createParser } = require('parse-pairs')
diff --git a/@xen-orchestra/backups/_lvm.js b/@xen-orchestra/backups/_lvm.js
index 1814b06700..7e95f805eb 100644
--- a/@xen-orchestra/backups/_lvm.js
+++ b/@xen-orchestra/backups/_lvm.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const fromCallback = require('promise-toolbox/fromCallback')
 const { createParser } = require('parse-pairs')
 const { execFile } = require('child_process')
diff --git a/@xen-orchestra/backups/_watchStreamSize.js b/@xen-orchestra/backups/_watchStreamSize.js
index 9a80cb6d9c..61bb4e0ae1 100644
--- a/@xen-orchestra/backups/_watchStreamSize.js
+++ b/@xen-orchestra/backups/_watchStreamSize.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.watchStreamSize = function watchStreamSize(stream, container = { size: 0 }) {
   stream.on('data', data => {
     container.size += data.length
diff --git a/@xen-orchestra/backups/formatVmBackups.js b/@xen-orchestra/backups/formatVmBackups.js
index 65bf1023d2..10dc5d8167 100644
--- a/@xen-orchestra/backups/formatVmBackups.js
+++ b/@xen-orchestra/backups/formatVmBackups.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const mapValues = require('lodash/mapValues.js')
 const { dirname } = require('path')
 
diff --git a/@xen-orchestra/backups/merge-worker/cli.js b/@xen-orchestra/backups/merge-worker/cli.js
index 43e9c7f770..f4b44549fb 100755
--- a/@xen-orchestra/backups/merge-worker/cli.js
+++ b/@xen-orchestra/backups/merge-worker/cli.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+'use strict'
+
 const { catchGlobalErrors } = require('@xen-orchestra/log/configure.js')
 const { createLogger } = require('@xen-orchestra/log')
 const { getSyncedHandler } = require('@xen-orchestra/fs')
diff --git a/@xen-orchestra/backups/merge-worker/index.js b/@xen-orchestra/backups/merge-worker/index.js
index e3aaaaaa10..6094bf7e0b 100644
--- a/@xen-orchestra/backups/merge-worker/index.js
+++ b/@xen-orchestra/backups/merge-worker/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { join, resolve } = require('path')
 const { spawn } = require('child_process')
 const { check } = require('proper-lockfile')
diff --git a/@xen-orchestra/backups/parseMetadataBackupId.js b/@xen-orchestra/backups/parseMetadataBackupId.js
index 3a8e26cafc..d125f99190 100644
--- a/@xen-orchestra/backups/parseMetadataBackupId.js
+++ b/@xen-orchestra/backups/parseMetadataBackupId.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { DIR_XO_CONFIG_BACKUPS, DIR_XO_POOL_METADATA_BACKUPS } = require('./RemoteAdapter.js')
 
 exports.parseMetadataBackupId = function parseMetadataBackupId(backupId) {
diff --git a/@xen-orchestra/backups/runBackupWorker.js b/@xen-orchestra/backups/runBackupWorker.js
index 58742f6213..c661761456 100644
--- a/@xen-orchestra/backups/runBackupWorker.js
+++ b/@xen-orchestra/backups/runBackupWorker.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const path = require('path')
 const { createLogger } = require('@xen-orchestra/log')
 const { fork } = require('child_process')
diff --git a/@xen-orchestra/backups/tests.fixtures.js b/@xen-orchestra/backups/tests.fixtures.js
index 999af46ac1..5509bd2f57 100644
--- a/@xen-orchestra/backups/tests.fixtures.js
+++ b/@xen-orchestra/backups/tests.fixtures.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // a valid footer of a 2
 exports.VHDFOOTER = {
   cookie: 'conectix',
diff --git a/@xen-orchestra/backups/writers/DeltaBackupWriter.js b/@xen-orchestra/backups/writers/DeltaBackupWriter.js
index 82c160bf9e..6a853dafc6 100644
--- a/@xen-orchestra/backups/writers/DeltaBackupWriter.js
+++ b/@xen-orchestra/backups/writers/DeltaBackupWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const map = require('lodash/map.js')
 const mapValues = require('lodash/mapValues.js')
diff --git a/@xen-orchestra/backups/writers/DeltaReplicationWriter.js b/@xen-orchestra/backups/writers/DeltaReplicationWriter.js
index 0fd99c7876..25852d03cc 100644
--- a/@xen-orchestra/backups/writers/DeltaReplicationWriter.js
+++ b/@xen-orchestra/backups/writers/DeltaReplicationWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { asyncMap, asyncMapSettled } = require('@xen-orchestra/async-map')
 const ignoreErrors = require('promise-toolbox/ignoreErrors')
 const { formatDateTime } = require('@xen-orchestra/xapi')
diff --git a/@xen-orchestra/backups/writers/FullBackupWriter.js b/@xen-orchestra/backups/writers/FullBackupWriter.js
index 67f10a1d9e..e965aed04f 100644
--- a/@xen-orchestra/backups/writers/FullBackupWriter.js
+++ b/@xen-orchestra/backups/writers/FullBackupWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { formatFilenameDate } = require('../_filenameDate.js')
 const { getOldEntries } = require('../_getOldEntries.js')
 const { getVmBackupDir } = require('../_getVmBackupDir.js')
diff --git a/@xen-orchestra/backups/writers/FullReplicationWriter.js b/@xen-orchestra/backups/writers/FullReplicationWriter.js
index dc22486a6d..ff006ae5f3 100644
--- a/@xen-orchestra/backups/writers/FullReplicationWriter.js
+++ b/@xen-orchestra/backups/writers/FullReplicationWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const ignoreErrors = require('promise-toolbox/ignoreErrors')
 const { asyncMap, asyncMapSettled } = require('@xen-orchestra/async-map')
 const { formatDateTime } = require('@xen-orchestra/xapi')
diff --git a/@xen-orchestra/backups/writers/_AbstractDeltaWriter.js b/@xen-orchestra/backups/writers/_AbstractDeltaWriter.js
index 9844003ba1..04eb78126b 100644
--- a/@xen-orchestra/backups/writers/_AbstractDeltaWriter.js
+++ b/@xen-orchestra/backups/writers/_AbstractDeltaWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { AbstractWriter } = require('./_AbstractWriter.js')
 
 exports.AbstractDeltaWriter = class AbstractDeltaWriter extends AbstractWriter {
diff --git a/@xen-orchestra/backups/writers/_AbstractFullWriter.js b/@xen-orchestra/backups/writers/_AbstractFullWriter.js
index 68c2371130..3ec2faceb4 100644
--- a/@xen-orchestra/backups/writers/_AbstractFullWriter.js
+++ b/@xen-orchestra/backups/writers/_AbstractFullWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { AbstractWriter } = require('./_AbstractWriter.js')
 
 exports.AbstractFullWriter = class AbstractFullWriter extends AbstractWriter {
diff --git a/@xen-orchestra/backups/writers/_AbstractWriter.js b/@xen-orchestra/backups/writers/_AbstractWriter.js
index 4a51ca99ae..d5313d9b9c 100644
--- a/@xen-orchestra/backups/writers/_AbstractWriter.js
+++ b/@xen-orchestra/backups/writers/_AbstractWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.AbstractWriter = class AbstractWriter {
   constructor({ backup, settings }) {
     this._backup = backup
diff --git a/@xen-orchestra/backups/writers/_MixinBackupWriter.js b/@xen-orchestra/backups/writers/_MixinBackupWriter.js
index 66b68eaa5d..159f8400bc 100644
--- a/@xen-orchestra/backups/writers/_MixinBackupWriter.js
+++ b/@xen-orchestra/backups/writers/_MixinBackupWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { createLogger } = require('@xen-orchestra/log')
 const { join } = require('path')
 
diff --git a/@xen-orchestra/backups/writers/_MixinReplicationWriter.js b/@xen-orchestra/backups/writers/_MixinReplicationWriter.js
index 80c8cd82b3..8814672118 100644
--- a/@xen-orchestra/backups/writers/_MixinReplicationWriter.js
+++ b/@xen-orchestra/backups/writers/_MixinReplicationWriter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.MixinReplicationWriter = (BaseClass = Object) =>
   class MixinReplicationWriter extends BaseClass {
     constructor({ sr, ...rest }) {
diff --git a/@xen-orchestra/backups/writers/_checkVhd.js b/@xen-orchestra/backups/writers/_checkVhd.js
index 56e54b44a2..b92be1c797 100644
--- a/@xen-orchestra/backups/writers/_checkVhd.js
+++ b/@xen-orchestra/backups/writers/_checkVhd.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const openVhd = require('vhd-lib').openVhd
 const Disposable = require('promise-toolbox/Disposable')
 
diff --git a/@xen-orchestra/backups/writers/_listReplicatedVms.js b/@xen-orchestra/backups/writers/_listReplicatedVms.js
index befae5560c..164d0ad9ae 100644
--- a/@xen-orchestra/backups/writers/_listReplicatedVms.js
+++ b/@xen-orchestra/backups/writers/_listReplicatedVms.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const getReplicatedVmDatetime = vm => {
   const { 'xo:backup:datetime': datetime = vm.name_label.slice(-17, -1) } = vm.other_config
   return datetime
diff --git a/@xen-orchestra/backups/writers/_packUuid.js b/@xen-orchestra/backups/writers/_packUuid.js
index f9950b775f..802350e9d1 100644
--- a/@xen-orchestra/backups/writers/_packUuid.js
+++ b/@xen-orchestra/backups/writers/_packUuid.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const PARSE_UUID_RE = /-/g
 
 exports.packUuid = function packUuid(uuid) {
diff --git a/@xen-orchestra/cr-seed-cli/index.js b/@xen-orchestra/cr-seed-cli/index.js
index 5a672c3198..42f3f7a86c 100755
--- a/@xen-orchestra/cr-seed-cli/index.js
+++ b/@xen-orchestra/cr-seed-cli/index.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+'use strict'
+
 const { Ref, Xapi } = require('xen-api')
 const { defer } = require('golike-defer')
 
diff --git a/@xen-orchestra/cron/.babelrc.js b/@xen-orchestra/cron/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/cron/.babelrc.js
+++ b/@xen-orchestra/cron/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/defined/index.js b/@xen-orchestra/defined/index.js
index 2aa930fdd4..923bb886f0 100644
--- a/@xen-orchestra/defined/index.js
+++ b/@xen-orchestra/defined/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // Usage:
 //
 // ```js
diff --git a/@xen-orchestra/emit-async/index.js b/@xen-orchestra/emit-async/index.js
index d5ae0ea229..817d854150 100644
--- a/@xen-orchestra/emit-async/index.js
+++ b/@xen-orchestra/emit-async/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 module.exports = function emitAsync(event) {
   let opts
   let i = 1
diff --git a/@xen-orchestra/fs/.babelrc.js b/@xen-orchestra/fs/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/fs/.babelrc.js
+++ b/@xen-orchestra/fs/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/log/configure.js b/@xen-orchestra/log/configure.js
index 8bb7cebaad..8e6655f4a8 100644
--- a/@xen-orchestra/log/configure.js
+++ b/@xen-orchestra/log/configure.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const createConsoleTransport = require('./transports/console')
 const { LEVELS, resolve } = require('./levels')
 const { compileGlobPattern } = require('./utils')
diff --git a/@xen-orchestra/log/index.js b/@xen-orchestra/log/index.js
index 87854c4969..2683dfe581 100644
--- a/@xen-orchestra/log/index.js
+++ b/@xen-orchestra/log/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const createTransport = require('./transports/console')
 const { LEVELS, resolve } = require('./levels')
 
diff --git a/@xen-orchestra/log/levels.js b/@xen-orchestra/log/levels.js
index a8a70a5f2f..da4ab200f0 100644
--- a/@xen-orchestra/log/levels.js
+++ b/@xen-orchestra/log/levels.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const LEVELS = Object.create(null)
 exports.LEVELS = LEVELS
 
diff --git a/@xen-orchestra/log/levels.spec.js b/@xen-orchestra/log/levels.spec.js
index 4b649c00e0..08c4f00745 100644
--- a/@xen-orchestra/log/levels.spec.js
+++ b/@xen-orchestra/log/levels.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { forEach, isInteger } = require('lodash')
diff --git a/@xen-orchestra/log/transports/console.js b/@xen-orchestra/log/transports/console.js
index 468fec381d..c5c7412339 100644
--- a/@xen-orchestra/log/transports/console.js
+++ b/@xen-orchestra/log/transports/console.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { LEVELS, NAMES } = require('../levels')
 
 const { DEBUG, ERROR, FATAL, INFO, WARN } = LEVELS
diff --git a/@xen-orchestra/log/transports/email.js b/@xen-orchestra/log/transports/email.js
index 78d4f19d57..9d6842881e 100644
--- a/@xen-orchestra/log/transports/email.js
+++ b/@xen-orchestra/log/transports/email.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const fromCallback = require('promise-toolbox/fromCallback')
 const nodemailer = require('nodemailer') // eslint-disable-line n/no-extraneous-import
 const prettyFormat = require('pretty-format') // eslint-disable-line n/no-extraneous-import
diff --git a/@xen-orchestra/log/transports/memory.js b/@xen-orchestra/log/transports/memory.js
index 28b4fb28a6..18aa870a0c 100644
--- a/@xen-orchestra/log/transports/memory.js
+++ b/@xen-orchestra/log/transports/memory.js
@@ -1,3 +1,5 @@
+'use strict'
+
 function createTransport() {
   const memoryLogger = log => {
     logs.push(log)
diff --git a/@xen-orchestra/log/transports/syslog.js b/@xen-orchestra/log/transports/syslog.js
index aa794541c1..e8321a9fdc 100644
--- a/@xen-orchestra/log/transports/syslog.js
+++ b/@xen-orchestra/log/transports/syslog.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const fromCallback = require('promise-toolbox/fromCallback')
 const splitHost = require('split-host')
 const { createClient, Facility, Severity, Transport } = require('syslog-client')
diff --git a/@xen-orchestra/log/utils.js b/@xen-orchestra/log/utils.js
index b0a98ff5c2..df80f4ef80 100644
--- a/@xen-orchestra/log/utils.js
+++ b/@xen-orchestra/log/utils.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const escapeRegExp = require('lodash/escapeRegExp')
 
 // ===================================================================
diff --git a/@xen-orchestra/log/utils.spec.js b/@xen-orchestra/log/utils.spec.js
index b9bd75d54f..8c9813f0b9 100644
--- a/@xen-orchestra/log/utils.spec.js
+++ b/@xen-orchestra/log/utils.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const { compileGlobPattern } = require('./utils')
diff --git a/@xen-orchestra/mixin/index.js b/@xen-orchestra/mixin/index.js
index 6ec78054ae..7944da9473 100644
--- a/@xen-orchestra/mixin/index.js
+++ b/@xen-orchestra/mixin/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const camelCase = require('lodash/camelCase')
 
 const { defineProperties, defineProperty, keys } = Object
diff --git a/@xen-orchestra/mixin/legacy.js b/@xen-orchestra/mixin/legacy.js
index c2424412f0..25fa2465cc 100644
--- a/@xen-orchestra/mixin/legacy.js
+++ b/@xen-orchestra/mixin/legacy.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { getBoundPropertyDescriptor } = require('bind-property-descriptor')
 
 // ===================================================================
diff --git a/@xen-orchestra/mixins/Config.js b/@xen-orchestra/mixins/Config.js
index 5a5fe64782..e7d4bba394 100644
--- a/@xen-orchestra/mixins/Config.js
+++ b/@xen-orchestra/mixins/Config.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const get = require('lodash/get')
 const identity = require('lodash/identity')
 const isEqual = require('lodash/isEqual')
diff --git a/@xen-orchestra/mixins/Hooks.js b/@xen-orchestra/mixins/Hooks.js
index 9e2dc1e877..32d425da71 100644
--- a/@xen-orchestra/mixins/Hooks.js
+++ b/@xen-orchestra/mixins/Hooks.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const emitAsync = require('@xen-orchestra/emit-async')
 const EventEmitter = require('events')
diff --git a/@xen-orchestra/openflow/.babelrc.js b/@xen-orchestra/openflow/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/openflow/.babelrc.js
+++ b/@xen-orchestra/openflow/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/openflow/parse-socket.js b/@xen-orchestra/openflow/parse-socket.js
index c848a9f5e6..9cc9b310f7 100644
--- a/@xen-orchestra/openflow/parse-socket.js
+++ b/@xen-orchestra/openflow/parse-socket.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('./dist/parse-socket')
diff --git a/@xen-orchestra/proxy-cli/.babelrc.js b/@xen-orchestra/proxy-cli/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/proxy-cli/.babelrc.js
+++ b/@xen-orchestra/proxy-cli/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/self-signed/index.js b/@xen-orchestra/self-signed/index.js
index 1aebe75348..c83f14bc81 100644
--- a/@xen-orchestra/self-signed/index.js
+++ b/@xen-orchestra/self-signed/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { execFile } = require('child_process')
 
 const openssl = (cmd, args, { input, ...opts } = {}) =>
diff --git a/@xen-orchestra/template/.babelrc.js b/@xen-orchestra/template/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/template/.babelrc.js
+++ b/@xen-orchestra/template/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/upload-ova/.babelrc.js b/@xen-orchestra/upload-ova/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/upload-ova/.babelrc.js
+++ b/@xen-orchestra/upload-ova/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/@xen-orchestra/upload-ova/src/config.js b/@xen-orchestra/upload-ova/src/config.js
index d7d0a37270..e64e8c8921 100644
--- a/@xen-orchestra/upload-ova/src/config.js
+++ b/@xen-orchestra/upload-ova/src/config.js
@@ -1,7 +1,3 @@
-'use strict'
-
-// ===================================================================
-
 import assign from 'lodash/assign'
 import get_ from 'lodash/get'
 import unset_ from 'lodash/unset'
diff --git a/@xen-orchestra/xapi/.babelrc.js b/@xen-orchestra/xapi/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/@xen-orchestra/xapi/.babelrc.js
+++ b/@xen-orchestra/xapi/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/complex-matcher/.babelrc.js b/packages/complex-matcher/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/complex-matcher/.babelrc.js
+++ b/packages/complex-matcher/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/value-matcher/.babelrc.js b/packages/value-matcher/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/value-matcher/.babelrc.js
+++ b/packages/value-matcher/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/vhd-cli/.babelrc.js b/packages/vhd-cli/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/vhd-cli/.babelrc.js
+++ b/packages/vhd-cli/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/vhd-lib/Vhd/VhdAbstract.integ.spec.js b/packages/vhd-lib/Vhd/VhdAbstract.integ.spec.js
index 53834838e7..e9b0e25184 100644
--- a/packages/vhd-lib/Vhd/VhdAbstract.integ.spec.js
+++ b/packages/vhd-lib/Vhd/VhdAbstract.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const rimraf = require('rimraf')
diff --git a/packages/vhd-lib/Vhd/VhdAbstract.js b/packages/vhd-lib/Vhd/VhdAbstract.js
index a752723512..a83ecf56e8 100644
--- a/packages/vhd-lib/Vhd/VhdAbstract.js
+++ b/packages/vhd-lib/Vhd/VhdAbstract.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const {
   computeBatSize,
   computeFullBlockSize,
diff --git a/packages/vhd-lib/Vhd/VhdDirectory.integ.spec.js b/packages/vhd-lib/Vhd/VhdDirectory.integ.spec.js
index 703942f5f5..69d240a7ae 100644
--- a/packages/vhd-lib/Vhd/VhdDirectory.integ.spec.js
+++ b/packages/vhd-lib/Vhd/VhdDirectory.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const rimraf = require('rimraf')
diff --git a/packages/vhd-lib/Vhd/VhdDirectory.js b/packages/vhd-lib/Vhd/VhdDirectory.js
index db3d071357..e68a8927cc 100644
--- a/packages/vhd-lib/Vhd/VhdDirectory.js
+++ b/packages/vhd-lib/Vhd/VhdDirectory.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { unpackHeader, unpackFooter, sectorsToBytes } = require('./_utils')
 const { createLogger } = require('@xen-orchestra/log')
 const { fuFooter, fuHeader, checksumStruct } = require('../_structs')
diff --git a/packages/vhd-lib/Vhd/VhdFile.integ.spec.js b/packages/vhd-lib/Vhd/VhdFile.integ.spec.js
index 5a9292de64..acea27ff2f 100644
--- a/packages/vhd-lib/Vhd/VhdFile.integ.spec.js
+++ b/packages/vhd-lib/Vhd/VhdFile.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const execa = require('execa')
diff --git a/packages/vhd-lib/Vhd/VhdFile.js b/packages/vhd-lib/Vhd/VhdFile.js
index 38310dfce0..72ebb06429 100644
--- a/packages/vhd-lib/Vhd/VhdFile.js
+++ b/packages/vhd-lib/Vhd/VhdFile.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const {
   BLOCK_UNUSED,
   FOOTER_SIZE,
diff --git a/packages/vhd-lib/Vhd/VhdSynthetic.integ.spec.js b/packages/vhd-lib/Vhd/VhdSynthetic.integ.spec.js
index dd671fe72e..8181d50840 100644
--- a/packages/vhd-lib/Vhd/VhdSynthetic.integ.spec.js
+++ b/packages/vhd-lib/Vhd/VhdSynthetic.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const rimraf = require('rimraf')
diff --git a/packages/vhd-lib/Vhd/VhdSynthetic.js b/packages/vhd-lib/Vhd/VhdSynthetic.js
index 8764dffb35..064c8ee2e5 100644
--- a/packages/vhd-lib/Vhd/VhdSynthetic.js
+++ b/packages/vhd-lib/Vhd/VhdSynthetic.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const UUID = require('uuid')
 const cloneDeep = require('lodash/cloneDeep.js')
 const { asyncMap } = require('@xen-orchestra/async-map')
diff --git a/packages/vhd-lib/Vhd/_utils.js b/packages/vhd-lib/Vhd/_utils.js
index 3fca5fe576..062863792d 100644
--- a/packages/vhd-lib/Vhd/_utils.js
+++ b/packages/vhd-lib/Vhd/_utils.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const { BLOCK_UNUSED, SECTOR_SIZE } = require('../_constants')
 const { fuFooter, fuHeader, checksumStruct, unpackField } = require('../_structs')
diff --git a/packages/vhd-lib/_bitmap.js b/packages/vhd-lib/_bitmap.js
index 1633f7a3fd..29a8a76084 100644
--- a/packages/vhd-lib/_bitmap.js
+++ b/packages/vhd-lib/_bitmap.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const MASK = 0x80
 
 exports.set = (map, bit) => {
diff --git a/packages/vhd-lib/_checkHeader.js b/packages/vhd-lib/_checkHeader.js
index d8ed768ddb..5a1b3d21c8 100644
--- a/packages/vhd-lib/_checkHeader.js
+++ b/packages/vhd-lib/_checkHeader.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 
 const { HEADER_COOKIE, HEADER_VERSION, SECTOR_SIZE } = require('./_constants')
diff --git a/packages/vhd-lib/_computeGeometryForSize.js b/packages/vhd-lib/_computeGeometryForSize.js
index c658387e7f..e83b7c018a 100644
--- a/packages/vhd-lib/_computeGeometryForSize.js
+++ b/packages/vhd-lib/_computeGeometryForSize.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { SECTOR_SIZE } = require('./_constants')
 
 module.exports = function computeGeometryForSize(size) {
diff --git a/packages/vhd-lib/_constants.js b/packages/vhd-lib/_constants.js
index ae7448d55e..6b593803e3 100644
--- a/packages/vhd-lib/_constants.js
+++ b/packages/vhd-lib/_constants.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.BLOCK_UNUSED = 0xffffffff
 
 // This lib has been extracted from the Xen Orchestra project.
diff --git a/packages/vhd-lib/_createFooterHeader.integ.spec.js b/packages/vhd-lib/_createFooterHeader.integ.spec.js
index f77861478b..df06ba7535 100644
--- a/packages/vhd-lib/_createFooterHeader.integ.spec.js
+++ b/packages/vhd-lib/_createFooterHeader.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 const { createFooter } = require('./_createFooterHeader')
 
diff --git a/packages/vhd-lib/_createFooterHeader.js b/packages/vhd-lib/_createFooterHeader.js
index 40a9cb789c..bae86fc2fc 100644
--- a/packages/vhd-lib/_createFooterHeader.js
+++ b/packages/vhd-lib/_createFooterHeader.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { v4: generateUuid } = require('uuid')
 
 const { checksumStruct, fuFooter, fuHeader } = require('./_structs')
diff --git a/packages/vhd-lib/_getFirstAndLastBlocks.js b/packages/vhd-lib/_getFirstAndLastBlocks.js
index 1e46a1b366..40016c9e87 100644
--- a/packages/vhd-lib/_getFirstAndLastBlocks.js
+++ b/packages/vhd-lib/_getFirstAndLastBlocks.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 
 const { BLOCK_UNUSED } = require('./_constants')
diff --git a/packages/vhd-lib/_noop.js b/packages/vhd-lib/_noop.js
index 8124ddd9ef..6aedb787bb 100644
--- a/packages/vhd-lib/_noop.js
+++ b/packages/vhd-lib/_noop.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = Function.prototype
diff --git a/packages/vhd-lib/_resolveRelativeFromFile.js b/packages/vhd-lib/_resolveRelativeFromFile.js
index c178bc0b34..36ca069cdb 100644
--- a/packages/vhd-lib/_resolveRelativeFromFile.js
+++ b/packages/vhd-lib/_resolveRelativeFromFile.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { dirname, resolve } = require('path')
 
 const resolveRelativeFromFile = (file, path) => resolve('/', dirname(file), path).slice(1)
diff --git a/packages/vhd-lib/_structs.js b/packages/vhd-lib/_structs.js
index 1693ea554a..85b840662e 100644
--- a/packages/vhd-lib/_structs.js
+++ b/packages/vhd-lib/_structs.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const fu = require('struct-fu')
 
diff --git a/packages/vhd-lib/aliases.integ.spec.js b/packages/vhd-lib/aliases.integ.spec.js
index 710a606ad9..074eb72771 100644
--- a/packages/vhd-lib/aliases.integ.spec.js
+++ b/packages/vhd-lib/aliases.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const rimraf = require('rimraf')
diff --git a/packages/vhd-lib/aliases.js b/packages/vhd-lib/aliases.js
index 8cf83ebcd1..f43864c807 100644
--- a/packages/vhd-lib/aliases.js
+++ b/packages/vhd-lib/aliases.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { ALIAS_MAX_PATH_LENGTH } = require('./_constants')
 const resolveRelativeFromFile = require('./_resolveRelativeFromFile')
 
diff --git a/packages/vhd-lib/chain.js b/packages/vhd-lib/chain.js
index 035d19c4a6..776227e44b 100644
--- a/packages/vhd-lib/chain.js
+++ b/packages/vhd-lib/chain.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { dirname, relative } = require('path')
 
 const { openVhd } = require('./openVhd')
diff --git a/packages/vhd-lib/checkChain.js b/packages/vhd-lib/checkChain.js
index ea18e2b341..bb1b8c197c 100644
--- a/packages/vhd-lib/checkChain.js
+++ b/packages/vhd-lib/checkChain.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { openVhd } = require('./openVhd')
 const resolveRelativeFromFile = require('./_resolveRelativeFromFile')
 const { DISK_TYPES } = require('./_constants')
diff --git a/packages/vhd-lib/checkFooter.js b/packages/vhd-lib/checkFooter.js
index 4352c0e8ff..a4915d727e 100644
--- a/packages/vhd-lib/checkFooter.js
+++ b/packages/vhd-lib/checkFooter.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 
 const { DISK_TYPES, FILE_FORMAT_VERSION, FOOTER_COOKIE, FOOTER_SIZE } = require('./_constants')
diff --git a/packages/vhd-lib/createReadableSparseStream.js b/packages/vhd-lib/createReadableSparseStream.js
index ebcf9b8f7d..49e9327bdb 100644
--- a/packages/vhd-lib/createReadableSparseStream.js
+++ b/packages/vhd-lib/createReadableSparseStream.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const asyncIteratorToStream = require('async-iterator-to-stream')
 const { forEachRight } = require('lodash')
diff --git a/packages/vhd-lib/createVhdDirectoryFromStream.js b/packages/vhd-lib/createVhdDirectoryFromStream.js
index 12675348b8..d950658794 100644
--- a/packages/vhd-lib/createVhdDirectoryFromStream.js
+++ b/packages/vhd-lib/createVhdDirectoryFromStream.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { parseVhdStream } = require('./parseVhdStream.js')
 const { VhdDirectory } = require('./Vhd/VhdDirectory.js')
 const { Disposable } = require('promise-toolbox')
diff --git a/packages/vhd-lib/createVhdStreamWithLength.integ.spec.js b/packages/vhd-lib/createVhdStreamWithLength.integ.spec.js
index de91ba7b04..bf6e6914d0 100644
--- a/packages/vhd-lib/createVhdStreamWithLength.integ.spec.js
+++ b/packages/vhd-lib/createVhdStreamWithLength.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const execa = require('execa')
diff --git a/packages/vhd-lib/createVhdStreamWithLength.js b/packages/vhd-lib/createVhdStreamWithLength.js
index ded43c5c88..3321abed3e 100644
--- a/packages/vhd-lib/createVhdStreamWithLength.js
+++ b/packages/vhd-lib/createVhdStreamWithLength.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const assert = require('assert')
 const { pipeline, Transform } = require('readable-stream')
 const { readChunk } = require('@vates/read-chunk')
diff --git a/packages/vhd-lib/index.js b/packages/vhd-lib/index.js
index 65b0376c55..a920a419a7 100644
--- a/packages/vhd-lib/index.js
+++ b/packages/vhd-lib/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.chainVhd = require('./chain')
 exports.checkFooter = require('./checkFooter')
 exports.checkVhdChain = require('./checkChain')
diff --git a/packages/vhd-lib/merge.integ.spec.js b/packages/vhd-lib/merge.integ.spec.js
index 28826d2974..660521b880 100644
--- a/packages/vhd-lib/merge.integ.spec.js
+++ b/packages/vhd-lib/merge.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const fs = require('fs-extra')
diff --git a/packages/vhd-lib/merge.js b/packages/vhd-lib/merge.js
index c12054d663..b9e857e493 100644
--- a/packages/vhd-lib/merge.js
+++ b/packages/vhd-lib/merge.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // TODO: remove once completely merged in vhd.js
 
 const assert = require('assert')
diff --git a/packages/vhd-lib/openVhd.integ.spec.js b/packages/vhd-lib/openVhd.integ.spec.js
index 4844c4334b..f6b84102cb 100644
--- a/packages/vhd-lib/openVhd.integ.spec.js
+++ b/packages/vhd-lib/openVhd.integ.spec.js
@@ -1,3 +1,5 @@
+'use strict'
+
 /* eslint-env jest */
 
 const rimraf = require('rimraf')
diff --git a/packages/vhd-lib/openVhd.js b/packages/vhd-lib/openVhd.js
index 0bc67eb4bf..8852cbafe4 100644
--- a/packages/vhd-lib/openVhd.js
+++ b/packages/vhd-lib/openVhd.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { resolveVhdAlias } = require('./aliases')
 const { VhdDirectory } = require('./Vhd/VhdDirectory.js')
 const { VhdFile } = require('./Vhd/VhdFile.js')
diff --git a/packages/vhd-lib/parseVhdStream.js b/packages/vhd-lib/parseVhdStream.js
index 1c277fed58..ed03e68e11 100644
--- a/packages/vhd-lib/parseVhdStream.js
+++ b/packages/vhd-lib/parseVhdStream.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { BLOCK_UNUSED, FOOTER_SIZE, HEADER_SIZE, SECTOR_SIZE } = require('./_constants')
 const { readChunk } = require('@vates/read-chunk')
 const assert = require('assert')
diff --git a/packages/vhd-lib/peekFooterFromVhdStream.js b/packages/vhd-lib/peekFooterFromVhdStream.js
index 06eec3e1cd..baf4fab890 100644
--- a/packages/vhd-lib/peekFooterFromVhdStream.js
+++ b/packages/vhd-lib/peekFooterFromVhdStream.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { readChunk } = require('@vates/read-chunk')
 
 const { FOOTER_SIZE } = require('./_constants')
diff --git a/packages/vhd-lib/tests/utils.js b/packages/vhd-lib/tests/utils.js
index 6c68990192..620891220d 100644
--- a/packages/vhd-lib/tests/utils.js
+++ b/packages/vhd-lib/tests/utils.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { pFromCallback } = require('promise-toolbox')
 const { pipeline } = require('readable-stream')
 const asyncIteratorToStream = require('async-iterator-to-stream')
diff --git a/packages/xapi-explore-sr/.babelrc.js b/packages/xapi-explore-sr/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xapi-explore-sr/.babelrc.js
+++ b/packages/xapi-explore-sr/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xen-api/.babelrc.js b/packages/xen-api/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xen-api/.babelrc.js
+++ b/packages/xen-api/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xen-api/examples/utils.js b/packages/xen-api/examples/utils.js
index 9ef5b07adb..a5a8c90b5e 100644
--- a/packages/xen-api/examples/utils.js
+++ b/packages/xen-api/examples/utils.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { createReadStream, createWriteStream, statSync } = require('fs')
 const { fromCallback } = require('promise-toolbox')
 const { PassThrough, pipeline } = require('readable-stream')
diff --git a/packages/xo-cli/.babelrc.js b/packages/xo-cli/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-cli/.babelrc.js
+++ b/packages/xo-cli/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-cli/src/config.js b/packages/xo-cli/src/config.js
index bc754190e2..017a6970c6 100644
--- a/packages/xo-cli/src/config.js
+++ b/packages/xo-cli/src/config.js
@@ -1,7 +1,3 @@
-'use strict'
-
-// ===================================================================
-
 const { readFile, writeFile } = require('fs/promises')
 
 const get = require('lodash/get')
diff --git a/packages/xo-cli/src/index.js b/packages/xo-cli/src/index.js
index 3436430410..51d632d355 100755
--- a/packages/xo-cli/src/index.js
+++ b/packages/xo-cli/src/index.js
@@ -1,7 +1,5 @@
 #!/usr/bin/env node
 
-'use strict'
-
 const createReadStream = require('fs').createReadStream
 const createWriteStream = require('fs').createWriteStream
 const stat = require('fs-extra').stat
diff --git a/packages/xo-collection/.babelrc.js b/packages/xo-collection/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-collection/.babelrc.js
+++ b/packages/xo-collection/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-collection/index.js b/packages/xo-collection/index.js
index aae59039c1..9ca513441f 100644
--- a/packages/xo-collection/index.js
+++ b/packages/xo-collection/index.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('./dist/index')
diff --git a/packages/xo-collection/unique-index.js b/packages/xo-collection/unique-index.js
index 9f9d92cd51..1df545e80d 100644
--- a/packages/xo-collection/unique-index.js
+++ b/packages/xo-collection/unique-index.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('./dist/unique-index')
diff --git a/packages/xo-collection/view.js b/packages/xo-collection/view.js
index 6e691e6c22..73a53b10be 100644
--- a/packages/xo-collection/view.js
+++ b/packages/xo-collection/view.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('./dist/view')
diff --git a/packages/xo-common/.babelrc.js b/packages/xo-common/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-common/.babelrc.js
+++ b/packages/xo-common/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-common/api-errors.js b/packages/xo-common/api-errors.js
index 3b3e7974b6..b31c1a3773 100644
--- a/packages/xo-common/api-errors.js
+++ b/packages/xo-common/api-errors.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('./dist/api-errors')
diff --git a/packages/xo-lib/.babelrc.js b/packages/xo-lib/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-lib/.babelrc.js
+++ b/packages/xo-lib/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-remote-parser/.babelrc.js b/packages/xo-remote-parser/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-remote-parser/.babelrc.js
+++ b/packages/xo-remote-parser/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-audit/.babelrc.js b/packages/xo-server-audit/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-audit/.babelrc.js
+++ b/packages/xo-server-audit/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-auth-github/.babelrc.js b/packages/xo-server-auth-github/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-auth-github/.babelrc.js
+++ b/packages/xo-server-auth-github/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-auth-google/.babelrc.js b/packages/xo-server-auth-google/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-auth-google/.babelrc.js
+++ b/packages/xo-server-auth-google/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-auth-ldap/.babelrc.js b/packages/xo-server-auth-ldap/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-auth-ldap/.babelrc.js
+++ b/packages/xo-server-auth-ldap/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-auth-saml/.babelrc.js b/packages/xo-server-auth-saml/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-auth-saml/.babelrc.js
+++ b/packages/xo-server-auth-saml/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-backup-reports/.babelrc.js b/packages/xo-server-backup-reports/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-backup-reports/.babelrc.js
+++ b/packages/xo-server-backup-reports/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-load-balancer/.babelrc.js b/packages/xo-server-load-balancer/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-load-balancer/.babelrc.js
+++ b/packages/xo-server-load-balancer/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-netbox/.babelrc.js b/packages/xo-server-netbox/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-netbox/.babelrc.js
+++ b/packages/xo-server-netbox/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-perf-alert/.babelrc.js b/packages/xo-server-perf-alert/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-perf-alert/.babelrc.js
+++ b/packages/xo-server-perf-alert/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-sdn-controller/.babelrc.js b/packages/xo-server-sdn-controller/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-sdn-controller/.babelrc.js
+++ b/packages/xo-server-sdn-controller/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-test-plugin/index.js b/packages/xo-server-test-plugin/index.js
index 4cc96140d0..8490098332 100644
--- a/packages/xo-server-test-plugin/index.js
+++ b/packages/xo-server-test-plugin/index.js
@@ -1,3 +1,5 @@
+'use strict'
+
 // This is one of the simplest xo-server's plugin than can be created.
 
 // This (optional) schema is used to describe the expected
diff --git a/packages/xo-server-test/.babelrc.js b/packages/xo-server-test/.babelrc.js
index 83b9aab03a..64023da1ca 100644
--- a/packages/xo-server-test/.babelrc.js
+++ b/packages/xo-server-test/.babelrc.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const pkg = require('./package.json')
 
 // `xo-server-test` is a special package which has no dev dependencies but our
diff --git a/packages/xo-server-transport-email/.babelrc.js b/packages/xo-server-transport-email/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-transport-email/.babelrc.js
+++ b/packages/xo-server-transport-email/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-transport-icinga2/.babelrc.js b/packages/xo-server-transport-icinga2/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-transport-icinga2/.babelrc.js
+++ b/packages/xo-server-transport-icinga2/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-transport-nagios/.babelrc.js b/packages/xo-server-transport-nagios/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-transport-nagios/.babelrc.js
+++ b/packages/xo-server-transport-nagios/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-transport-slack/.babelrc.js b/packages/xo-server-transport-slack/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-transport-slack/.babelrc.js
+++ b/packages/xo-server-transport-slack/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-transport-xmpp/.babelrc.js b/packages/xo-server-transport-xmpp/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-transport-xmpp/.babelrc.js
+++ b/packages/xo-server-transport-xmpp/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-usage-report/.babelrc.js b/packages/xo-server-usage-report/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-usage-report/.babelrc.js
+++ b/packages/xo-server-usage-report/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-server-web-hooks/.babelrc.js b/packages/xo-server-web-hooks/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-server-web-hooks/.babelrc.js
+++ b/packages/xo-server-web-hooks/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-vmdk-to-vhd/.babelrc.js b/packages/xo-vmdk-to-vhd/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-vmdk-to-vhd/.babelrc.js
+++ b/packages/xo-vmdk-to-vhd/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-vmdk-to-vhd/src/virtual-buffer.js b/packages/xo-vmdk-to-vhd/src/virtual-buffer.js
index e0614d88eb..3f34351158 100644
--- a/packages/xo-vmdk-to-vhd/src/virtual-buffer.js
+++ b/packages/xo-vmdk-to-vhd/src/virtual-buffer.js
@@ -1,5 +1,3 @@
-'use strict'
-
 export class VirtualBuffer {
   constructor(readStream) {
     this._readStream = readStream
diff --git a/packages/xo-web/.babelrc.js b/packages/xo-web/.babelrc.js
index 21d371d728..3a9c8ad3d4 100644
--- a/packages/xo-web/.babelrc.js
+++ b/packages/xo-web/.babelrc.js
@@ -1 +1,3 @@
+'use strict'
+
 module.exports = require('../../@xen-orchestra/babel-config')(require('./package.json'))
diff --git a/packages/xo-web/setup-tests.js b/packages/xo-web/setup-tests.js
index 89def87f6a..1a19d487aa 100644
--- a/packages/xo-web/setup-tests.js
+++ b/packages/xo-web/setup-tests.js
@@ -1,3 +1,5 @@
+'use strict'
+
 import { configure } from 'enzyme'
 import Adapter from 'enzyme-adapter-react-15'