diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index e0688721922..54a9aa0534d 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -202,8 +202,6 @@ static type_lock tcl_lock = 0;
 
 #endif
 
-extern int Tk_GetNumMainWindows();
-
 #ifdef macintosh
 
 /*