diff --git a/ui_darwin.h b/ui_darwin.h
index 2a34ef44..b3df5cc2 100644
--- a/ui_darwin.h
+++ b/ui_darwin.h
@@ -11,6 +11,10 @@ This file assumes that you have imported <Cocoa/Cocoa.h> and "ui.h" beforehand.
 extern "C" {
 #endif
 
+struct uiControlOSVtable {
+	size_t Size;
+};
+
 #ifdef __cplusplus
 }
 #endif