diff --git a/run_tests.py b/run_tests.py
index 0fdde8c020e8cc6da7f8a7312ad821c347068ad1..cbc9dc30a5837acddd375910e4e4e482cc7b7713 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -4,13 +4,13 @@ import unittest
 
 
 # Run all tests
-def main(args=None):
+def main(pattern='test_*.py', *args):
     test_loader = unittest.TestLoader()
-    test_suite = test_loader.discover('tests', pattern='test_*.py')
+    test_suite = test_loader.discover('tests', pattern=pattern)
     runner = unittest.TextTestRunner()
     results = runner.run(test_suite)
     return results.wasSuccessful()
 
 
 if __name__ == '__main__':
-    sys.exit(0 if main(sys.argv[1:]) else 1)
+    sys.exit(0 if main(*sys.argv[1:]) else 1)