diff --git a/lisp/international/fontset.el b/lisp/international/fontset.el
index 3deaff9677..0236cd790a 100644
--- a/lisp/international/fontset.el
+++ b/lisp/international/fontset.el
@@ -795,10 +795,12 @@ setup-default-fontset
 			   (#x1D7F6 #x1D7FF mathematical-monospace)))
     (let ((slot (assq (nth 2 math-subgroup) script-representative-chars)))
       (if slot
-	  (if (vectorp (cdr slot))
-	      (setcdr slot (vconcat (cdr slot) (vector (car math-subgroup))))
-	    (setcdr slot (vector (cadr slot) (car math-subgroup))))
-	(setq slot (list (nth 2 math-subgroup) (car math-subgroup)))
+          (setcdr slot (append (list (car math-subgroup)
+                                     (cadr math-subgroup))
+                               (cdr slot)))
+	(setq slot (list (nth 2 math-subgroup)
+                         (car math-subgroup)
+                         (cadr math-subgroup)))
 	(nconc script-representative-chars (list slot))))
     (set-fontset-font
      "fontset-default"