diff --git a/acm/acm.el b/acm/acm.el
index 46dd05a1cb..22978a1333 100644
--- a/acm/acm.el
+++ b/acm/acm.el
@@ -185,7 +185,7 @@
   :type 'string
   :group 'acm)
 
-(defalias 'acm-completion-backend-merge-order 'acm-backend-order)
+(defvaralias 'acm-completion-backend-merge-order 'acm-backend-order)
 
 (defcustom acm-backend-order '("mode-first-part-candidates"
                                "template-first-part-candidates"