diff --git a/packages/xo-server/src/remote-handlers/abstract.js b/packages/xo-server/src/remote-handlers/abstract.js
index 1eb584d22..329015772 100644
--- a/packages/xo-server/src/remote-handlers/abstract.js
+++ b/packages/xo-server/src/remote-handlers/abstract.js
@@ -3,12 +3,9 @@ import through2 from 'through2'
 import { ignoreErrors } from 'promise-toolbox'
 import { parse } from 'xo-remote-parser'
 
-import {
-  addChecksumToReadStream,
-  getPseudoRandomBytes,
-  streamToBuffer,
-  validChecksumOfReadStream,
-} from '../utils'
+import { getPseudoRandomBytes, streamToBuffer } from '../utils'
+
+import { addChecksumToReadStream, validChecksumOfReadStream } from './checksum'
 
 const checksumFile = file => file + '.checksum'
 
diff --git a/packages/xo-server/src/remote-handlers/checksum.js b/packages/xo-server/src/remote-handlers/checksum.js
new file mode 100644
index 000000000..a9a9ee430
--- /dev/null
+++ b/packages/xo-server/src/remote-handlers/checksum.js
@@ -0,0 +1,95 @@
+import invert from 'lodash/invert'
+import through2 from 'through2'
+import { createHash } from 'crypto'
+import { defer, fromEvent } from 'promise-toolbox'
+
+const ALGORITHM_TO_ID = {
+  md5: '1',
+  sha256: '5',
+  sha512: '6',
+}
+
+const ID_TO_ALGORITHM = invert(ALGORITHM_TO_ID)
+
+// Wrap a readable stream in a stream with a checksum promise
+// attribute which is resolved at the end of an input stream.
+// (Finally .checksum contains the checksum of the input stream)
+//
+// Example:
+// const sourceStream = ...
+// const targetStream = ...
+// const checksumStream = addChecksumToReadStream(sourceStream)
+// await Promise.all([
+//   fromEvent(checksumStream.pipe(targetStream), 'finish'),
+//   checksumStream.checksum.then(console.log)
+// ])
+export const addChecksumToReadStream = (stream, algorithm = 'md5') => {
+  const algorithmId = ALGORITHM_TO_ID[algorithm]
+
+  if (!algorithmId) {
+    throw new Error(`unknown algorithm: ${algorithm}`)
+  }
+
+  const hash = createHash(algorithm)
+  const { promise, resolve } = defer()
+
+  const wrapper = stream.pipe(
+    through2(
+      (chunk, enc, callback) => {
+        hash.update(chunk)
+        callback(null, chunk)
+      },
+      callback => {
+        resolve(hash.digest('hex'))
+        callback()
+      }
+    )
+  )
+
+  stream.on('error', error => wrapper.emit('error', error))
+  wrapper.checksum = promise.then(hash => `$${algorithmId}$$${hash}`)
+
+  return wrapper
+}
+
+// Check if the checksum of a readable stream is equals to an expected checksum.
+// The given stream is wrapped in a stream which emits an error event
+// if the computed checksum is not equals to the expected checksum.
+export const validChecksumOfReadStream = (stream, expectedChecksum) => {
+  const algorithmId = expectedChecksum.slice(
+    1,
+    expectedChecksum.indexOf('$', 1)
+  )
+
+  if (!algorithmId) {
+    throw new Error(`unknown algorithm: ${algorithmId}`)
+  }
+
+  const hash = createHash(ID_TO_ALGORITHM[algorithmId])
+
+  const wrapper = stream.pipe(
+    through2(
+      { highWaterMark: 0 },
+      (chunk, enc, callback) => {
+        hash.update(chunk)
+        callback(null, chunk)
+      },
+      callback => {
+        const checksum = `$${algorithmId}$$${hash.digest('hex')}`
+
+        callback(
+          checksum !== expectedChecksum
+            ? new Error(
+              `Bad checksum (${checksum}), expected: ${expectedChecksum}`
+            )
+            : null
+        )
+      }
+    )
+  )
+
+  stream.on('error', error => wrapper.emit('error', error))
+  wrapper.checksumVerified = fromEvent(wrapper, 'end')
+
+  return wrapper
+}
diff --git a/packages/xo-server/src/utils.js b/packages/xo-server/src/utils.js
index 8af96cf6f..d81aca405 100644
--- a/packages/xo-server/src/utils.js
+++ b/packages/xo-server/src/utils.js
@@ -1,10 +1,8 @@
 import base64url from 'base64url'
-import eventToPromise from 'event-to-promise'
 import forEach from 'lodash/forEach'
 import has from 'lodash/has'
 import highland from 'highland'
 import humanFormat from 'human-format'
-import invert from 'lodash/invert'
 import isArray from 'lodash/isArray'
 import isString from 'lodash/isString'
 import keys from 'lodash/keys'
@@ -14,24 +12,21 @@ import multiKeyHashInt from 'multikey-hash'
 import pick from 'lodash/pick'
 import tmp from 'tmp'
 import xml2js from 'xml2js'
+import { randomBytes } from 'crypto'
 import { resolve } from 'path'
-
-// Moment timezone can be loaded only one time, it's a workaround to load
-// the latest version because cron module uses an old version of moment which
-// does not implement `guess` function for example.
-import 'moment-timezone'
-
-import through2 from 'through2'
 import { utcFormat, utcParse } from 'd3-time-format'
 import {
   all as pAll,
-  defer,
   fromCallback,
   isPromise,
   promisify,
   reflect as pReflect,
 } from 'promise-toolbox'
-import { createHash, randomBytes } from 'crypto'
+
+// Moment timezone can be loaded only one time, it's a workaround to load
+// the latest version because cron module uses an old version of moment which
+// does not implement `guess` function for example.
+import 'moment-timezone'
 
 // ===================================================================
 
@@ -106,99 +101,6 @@ export const diffItems = (coll1, coll2) => {
 
 // -------------------------------------------------------------------
 
-const ALGORITHM_TO_ID = {
-  md5: '1',
-  sha256: '5',
-  sha512: '6',
-}
-
-const ID_TO_ALGORITHM = invert(ALGORITHM_TO_ID)
-
-// Wrap a readable stream in a stream with a checksum promise
-// attribute which is resolved at the end of an input stream.
-// (Finally .checksum contains the checksum of the input stream)
-//
-// Example:
-// const sourceStream = ...
-// const targetStream = ...
-// const checksumStream = addChecksumToReadStream(sourceStream)
-// await Promise.all([
-//   eventToPromise(checksumStream.pipe(targetStream), 'finish'),
-//   checksumStream.checksum.then(console.log)
-// ])
-export const addChecksumToReadStream = (stream, algorithm = 'md5') => {
-  const algorithmId = ALGORITHM_TO_ID[algorithm]
-
-  if (!algorithmId) {
-    throw new Error(`unknown algorithm: ${algorithm}`)
-  }
-
-  const hash = createHash(algorithm)
-  const { promise, resolve } = defer()
-
-  const wrapper = stream.pipe(
-    through2(
-      (chunk, enc, callback) => {
-        hash.update(chunk)
-        callback(null, chunk)
-      },
-      callback => {
-        resolve(hash.digest('hex'))
-        callback()
-      }
-    )
-  )
-
-  stream.on('error', error => wrapper.emit('error', error))
-  wrapper.checksum = promise.then(hash => `$${algorithmId}$$${hash}`)
-
-  return wrapper
-}
-
-// Check if the checksum of a readable stream is equals to an expected checksum.
-// The given stream is wrapped in a stream which emits an error event
-// if the computed checksum is not equals to the expected checksum.
-export const validChecksumOfReadStream = (stream, expectedChecksum) => {
-  const algorithmId = expectedChecksum.slice(
-    1,
-    expectedChecksum.indexOf('$', 1)
-  )
-
-  if (!algorithmId) {
-    throw new Error(`unknown algorithm: ${algorithmId}`)
-  }
-
-  const hash = createHash(ID_TO_ALGORITHM[algorithmId])
-
-  const wrapper = stream.pipe(
-    through2(
-      { highWaterMark: 0 },
-      (chunk, enc, callback) => {
-        hash.update(chunk)
-        callback(null, chunk)
-      },
-      callback => {
-        const checksum = `$${algorithmId}$$${hash.digest('hex')}`
-
-        callback(
-          checksum !== expectedChecksum
-            ? new Error(
-              `Bad checksum (${checksum}), expected: ${expectedChecksum}`
-            )
-            : null
-        )
-      }
-    )
-  )
-
-  stream.on('error', error => wrapper.emit('error', error))
-  wrapper.checksumVerified = eventToPromise(wrapper, 'end')
-
-  return wrapper
-}
-
-// -------------------------------------------------------------------
-
 // Ensure the value is an array, wrap it if necessary.
 export function ensureArray (value) {
   if (value === undefined) {