diff --git a/tests/server/test_env.py b/tests/server/test_env.py
index fbc8f45..f5c2797 100644
--- a/tests/server/test_env.py
+++ b/tests/server/test_env.py
@@ -407,7 +407,7 @@ def test_tor_identity():
 def test_ban_versions():
     e = Env()
     assert e.drop_client is None
-    ban_re = '1\.[0-2]\.\d+?[_\w]*'
+    ban_re = r'1\.[0-2]\.\d+?[_\w]*'
     os.environ['DROP_CLIENT'] = ban_re
     e = Env()
     assert e.drop_client == re.compile(ban_re)