diff --git a/src/nsmenu.m b/src/nsmenu.m
index aab3016e5e8..05184660bac 100644
--- a/src/nsmenu.m
+++ b/src/nsmenu.m
@@ -1887,6 +1887,7 @@ - (void)dealloc
 - (Lisp_Object)runDialogAt: (NSPoint)p
 {
   int ret;
+  extern EMACS_TIME timer_check (int do_it_now); /* TODO: add to a header */
 
   /* initiate a session that will be ended by pop_down_menu */
   popupSession = [NSApp beginModalSessionForWindow: self];