diff --git a/src/editfns.c b/src/editfns.c
index 3fd3d91de33..9718c5aa153 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -2314,7 +2314,7 @@ Use %% to put a single % into the output.")
 	    /* Anything but a string, convert to a string using princ.  */
 	    register Lisp_Object tem;
 	    tem = Fprin1_to_string (args[n], Qt);
-	    if (STRING_MULTIBYTE (tem))
+	    if (STRING_MULTIBYTE (tem) & ! multibyte)
 	      {
 		multibyte = 1;
 		goto retry;