diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index eddd7b6407a..52019697ad7 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -2540,6 +2540,10 @@ This function is intended to be added to `auto-coding-functions'."
                   (bfcs-type
                    (coding-system-type buffer-file-coding-system)))
               (if (and enable-multibyte-characters
+                       ;; 'charset' will signal an error in
+                       ;; coding-system-equal, since it isn't a
+                       ;; coding-system.  So test that up front.
+                       (not (equal sym-type 'charset))
                        (coding-system-equal 'utf-8 sym-type)
                        (coding-system-equal 'utf-8 bfcs-type))
                   buffer-file-coding-system