diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index ef7afd37268..4be529624a4 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -1303,6 +1303,7 @@ REV is the revision to check out into WORKFILE."
 (autoload 'vc-do-async-command "vc-dispatcher")
 (autoload 'log-view-get-marked "log-view")
 (defvar compilation-directory)
+(defvar compilation-arguments)  ; defined in compile.el
 
 (defun vc-hg--pushpull (command prompt &optional obsolete)
   "Run COMMAND (a string; either push or pull) on the current Hg branch.