--- a/toolkit/modules/GMPUtils.jsm
+++ b/toolkit/modules/GMPUtils.jsm
@@ -7,16 +7,17 @@
 var EXPORTED_SYMBOLS = [ "GMP_PLUGIN_IDS",
                          "GMPPrefs",
                          "GMPUtils",
                          "OPEN_H264_ID",
                          "WIDEVINE_ID" ];
 
 const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
 const {AppConstants} = ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
+const {UpdateUtils} = ChromeUtils.import("resource://gre/modules/UpdateUtils.jsm");
 
 // GMP IDs
 const OPEN_H264_ID  = "gmp-gmpopenh264";
 const WIDEVINE_ID   = "gmp-widevinecdm";
 const GMP_PLUGIN_IDS = [ OPEN_H264_ID, WIDEVINE_ID ];
 
 var GMPUtils = {
   /**
@@ -90,16 +91,20 @@ var GMPUtils = {
    * in automated tests to override the checks that prevent GMPs running on an
    * unsupported platform.
    * @param   aPlugin
    *          The plugin to check.
    */
   _isPluginForceSupported(aPlugin) {
     return GMPPrefs.getBool(GMPPrefs.KEY_PLUGIN_FORCE_SUPPORTED, false, aPlugin.id);
   },
+
+  _isWindowsOnARM64() {
+    return AppConstants.platform == "win" && UpdateUtils.ABI.match(/aarch64/);
+  },
 };
 
 /**
  * Manages preferences for GMP addons
  */
 var GMPPrefs = {
   KEY_EME_ENABLED:              "media.eme.enabled",
   KEY_PLUGIN_ENABLED:           "media.{0}.enabled",