diff --git a/tests/client_test.py b/tests/client_test.py
index b921d88..932465c 100644
--- a/tests/client_test.py
+++ b/tests/client_test.py
@@ -222,7 +222,7 @@ def test_client_default_contentful_user_agent_headers(self):
         for e in expected:
             self.assertTrue(e in header)
 
-        self.assertTrue(re.search('os (Windows|macOS|Linux)(\/.*)?;', header))
+        self.assertTrue(re.search(r'os (Windows|macOS|Linux)(\/.*)?;', header))
 
         self.assertTrue('integration' not in header)
         self.assertTrue('app' not in header)
@@ -313,7 +313,7 @@ def test_client_with_all_headers(self):
         for e in expected:
             self.assertTrue(e in header)
 
-        self.assertTrue(re.search('os (Windows|macOS|Linux)(\/.*)?;', header))
+        self.assertTrue(re.search(r'os (Windows|macOS|Linux)(\/.*)?;', header))
 
     def test_client_headers(self):
         client = Client(
@@ -337,7 +337,7 @@ def test_client_headers(self):
         for e in expected:
             self.assertTrue(e in header)
 
-        self.assertTrue(re.search('os (Windows|macOS|Linux)(\/.*)?;', header))
+        self.assertTrue(re.search(r'os (Windows|macOS|Linux)(\/.*)?;', header))
 
     # Integration Tests