diff --git a/python/run_tests.sh b/python/run_tests.sh
index b8e3d91..fed6f11 100644
--- a/python/run_tests.sh
+++ b/python/run_tests.sh
@@ -2,6 +2,8 @@
 
 set -e
 set -x
+default_pythonpath=$PYTHONPATH:.
+export PYTHONPATH=${default_pythonpath:-.}
 for f in `ls tests/*.py`; do
 	python $f
 	if [ $? -gt 0 ]; then