diff --git a/Python/errors.c b/Python/errors.c
index 91ae730ae6e..cba3f0226b4 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -140,3 +140,9 @@ err_errno(exc)
 		DECREF(v);
 	return NULL;
 }
+
+void
+err_badcall()
+{
+	err_setstr(SystemError, "bad argument to internal function");
+}