diff --git a/lisp/vc.el b/lisp/vc.el
index 01b8b26d3bc..fd1c644fdf6 100644
--- a/lisp/vc.el
+++ b/lisp/vc.el
@@ -1512,7 +1512,7 @@ Return nil if there is no such person."
 	 (or (vc-backend-dispatch file "vcdiff" "rcsdiff")
 	     (vc-registration-error file))
 	 file
-	 "-q"
+	 (vc-backend-dispatch file nil "-q")
 	 (and oldvers (concat "-r" oldvers))
 	 (and newvers (concat "-r" newvers))
 	 (if (listp diff-switches)