diff --git a/src/py65/tests/test_memory.py b/src/py65/tests/test_memory.py
index 9ecf598..532de48 100644
--- a/src/py65/tests/test_memory.py
+++ b/src/py65/tests/test_memory.py
@@ -151,3 +151,5 @@ class ObservableMemoryTests(unittest.TestCase):
         subject = 0x10000 * [0x00] 
         return subject
 
+if __name__ == '__main__':
+    unittest.main()