Fix missing 'return NULL'
diff --git a/Objects/complexobject.c b/Objects/complexobject.c
index 894f796..7ebafa7 100644
--- a/Objects/complexobject.c
+++ b/Objects/complexobject.c
@@ -1027,7 +1027,7 @@
   overflow:
 	PyErr_SetString(PyExc_OverflowError,
 			"complex() arg overflow");
-
+	return NULL;
 }
 
 static PyObject *