diff --git a/lisp/international/mule-diag.el b/lisp/international/mule-diag.el
index ab50f01e0b8..18d477c1cb8 100644
--- a/lisp/international/mule-diag.el
+++ b/lisp/international/mule-diag.el
@@ -1107,7 +1107,6 @@ The list is null if CHAR isn't found in `unicodedata-file'."
       (error "`unicodedata-file' %s not found" unicodedata-file))
     (save-excursion
       (set-buffer (find-file-noselect unicodedata-file t t))
-      (toggle-read-only 1)
       (goto-char (point-min))
       (let ((hex (format "%04X" char))
 	    found first last)