diff --git a/src/nsfns.m b/src/nsfns.m
index 23f23375976..24fabbe2eaa 100644
--- a/src/nsfns.m
+++ b/src/nsfns.m
@@ -690,6 +690,16 @@ Turn the input menu (an NSMenu) into a lisp list for tracking on lisp side.
   SET_FRAME_GARBAGED (f);
 }
 
+#ifdef NS_IMPL_COCOA
+
+void
+ns_make_frame_key_window (struct frame *f)
+{
+  [[FRAME_NS_VIEW (f) window] makeKeyWindow];
+}
+
+#endif /* NS_IMPL_COCOA */
+
 /* tabbar support */
 static void
 ns_set_tab_bar_lines (struct frame *f, Lisp_Object value, Lisp_Object oldval)