diff --git a/lisp/international/mule-cmds.el b/lisp/international/mule-cmds.el
index bc656113428..bdf49c8de81 100644
--- a/lisp/international/mule-cmds.el
+++ b/lisp/international/mule-cmds.el
@@ -351,9 +351,6 @@ This also sets the following values:
     (setq default-process-coding-system
 	  (cons output-coding input-coding))))
 
-(defalias 'update-iso-coding-systems 'update-coding-systems-internal)
-(make-obsolete 'update-iso-coding-systems 'update-coding-systems-internal "20.3")
-
 (defun prefer-coding-system (coding-system)
   "Add CODING-SYSTEM at the front of the priority list for automatic detection.
 This also sets the following coding systems: