diff --git a/runtests.py b/runtests.py
index bb3074d..b060283 100755
--- a/runtests.py
+++ b/runtests.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python -Wd
 import sys
 from os.path import abspath, dirname