diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index b0f539ea3bd7..f6b0f5ace3fd 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1460,7 +1460,7 @@ pref("javascript.options.unboxed_objects",  false);
 pref("javascript.options.baselinejit",      true);
 //Duplicated in JitOptions - ensure both match.
 pref("javascript.options.baselinejit.threshold", 10);
-#ifdef _ARM64_
+#ifdef NO_ION
 pref("javascript.options.ion",              false);
 #else
 pref("javascript.options.ion",              true);
diff --git a/modules/libpref/moz.build b/modules/libpref/moz.build
index 25f7d9869d10..c56e0c7a64a3 100644
--- a/modules/libpref/moz.build
+++ b/modules/libpref/moz.build
@@ -49,6 +49,9 @@ DEFINES['MOZ_WIDGET_TOOLKIT'] = CONFIG['MOZ_WIDGET_TOOLKIT']
 if CONFIG['MOZ_ENABLE_WEBRENDER']:
     DEFINES['MOZ_ENABLE_WEBRENDER'] = True
 
+if CONFIG['CPU_ARCH'] == 'aarch64':
+    DEFINES['NO_ION'] = True
+
 FINAL_TARGET_PP_FILES += [
     'greprefs.js',
 ]