--- mmm-mode-0.4.8-orig/mmm-utils.el
+++ mmm-mode-0.4.8/mmm-utils.el
@@ -78,7 +78,11 @@
     (save-match-data
       (dolist (pair arg-pairs)
         (while (string-match (car pair) string)
-          (setq string (replace-match (cdr pair) t t string))))))
+          (setq string (replace-match
+			(if (fboundp 'format-mode-line)
+			    (format-mode-line (cdr pair))
+			  (cdr pair))
+			t t string))))))
   string)
 
 (defun mmm-format-matches (string &optional on-string)