diff --git a/lib/message-registry.js b/lib/message-registry.js
index e2111bc5..5496bf8e 100644
--- a/lib/message-registry.js
+++ b/lib/message-registry.js
@@ -3,7 +3,7 @@
 import { CompositeDisposable, Emitter } from 'atom'
 import debounce from 'lodash/debounce'
 import type { Disposable, TextBuffer } from 'atom'
-import { messageKey, updateKeys, createKeyMessageMap, flagMessages } from './helpers'
+import { messageKey, updateKeys, createKeyMessageMap, flagMessages, mergeArray } from './helpers'
 import type { MessagesPatch, Message, Linter } from './types'
 
 type Linter$Message$Map = {
@@ -52,26 +52,26 @@ class MessageRegistry {
     const result = { added: [], removed: [], messages: [] }
     for (const entry of this.messagesMap) {
       if (entry.deleted) {
-        result.removed = result.removed.concat(entry.oldMessages)
+        mergeArray(result.removed, entry.oldMessages)
         this.messagesMap.delete(entry)
         continue
       }
       if (!entry.changed) {
-        result.messages = result.messages.concat(entry.oldMessages)
+        mergeArray(result.messages, entry.oldMessages)
         continue
       }
       entry.changed = false
       if (!entry.oldMessages.length) {
         // All messages are new, no need to diff
         // NOTE: No need to add .key here because normalizeMessages already does that
-        result.added = result.added.concat(entry.messages)
-        result.messages = result.messages.concat(entry.messages)
+        mergeArray(result.added, entry.messages)
+        mergeArray(result.messages, entry.messages)
         entry.oldMessages = entry.messages
         continue
       }
       if (!entry.messages.length) {
         // All messages are old, no need to diff
-        result.removed = result.removed.concat(entry.oldMessages)
+        mergeArray(result.removed, entry.oldMessages)
         entry.oldMessages = []
         continue
       }
@@ -90,10 +90,10 @@ class MessageRegistry {
       // update the result and cache
       if (flaggedMessages !== null) {
         const { oldKept, oldRemoved, newAdded } = flaggedMessages
-        result.added = result.added.concat(newAdded)
-        result.removed = result.removed.concat(oldRemoved)
+        mergeArray(result.added, newAdded)
+        mergeArray(result.removed, oldRemoved)
         const allThisEntry = newAdded.concat(oldKept)
-        result.messages = result.messages.concat(allThisEntry)
+        mergeArray(result.messages, allThisEntry)
         entry.oldMessages = allThisEntry // update chache
       }
     }