diff --git a/core/lib/Drupal/Core/File/MimeType/ExtensionMimeTypeGuesser.php b/core/lib/Drupal/Core/File/MimeType/ExtensionMimeTypeGuesser.php
index 3ef7c519a44e776f81c81a1938c16d0b47a06ebb..9be8744533cf3255959ae79b73e3891868985284 100644
--- a/core/lib/Drupal/Core/File/MimeType/ExtensionMimeTypeGuesser.php
+++ b/core/lib/Drupal/Core/File/MimeType/ExtensionMimeTypeGuesser.php
@@ -621,7 +621,6 @@ class ExtensionMimeTypeGuesser implements MimeTypeGuesserInterface {
       'kar' => 187,
       'mpega' => 188,
       'mpga' => 188,
-      'm4a' => 188,
       'mp3' => 188,
       'mp2' => 188,
       'ogg' => 189,
@@ -848,6 +847,7 @@ class ExtensionMimeTypeGuesser implements MimeTypeGuesserInterface {
       'vrml' => 345,
       'f4a' => 346,
       'f4b' => 346,
+      'm4a' => 346,
       'flv' => 347,
       'm4v' => 348,
       'azw' => 349,