diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index 2199420fd3c..5b55c4ff025 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -875,8 +875,8 @@ like `mime-charset' as well as the current style like `:mime-charset'."
 Two coding systems are identical if two symbols are equal
 or one is an alias of the other."
   (or (eq coding-system-1 coding-system-2)
-      (and (equal (coding-system-spec coding-system-1)
-		  (coding-system-spec coding-system-2))
+      (and (equal (coding-system-plist coding-system-1)
+		  (coding-system-plist coding-system-2))
 	   (let ((eol-type-1 (coding-system-eol-type coding-system-1))
 		 (eol-type-2 (coding-system-eol-type coding-system-2)))
 	     (or (eq eol-type-1 eol-type-2)