diff --git a/kiosk/kiosk_browser/browser_widget.py b/kiosk/kiosk_browser/browser_widget.py
index ae410663..739de95a 100644
--- a/kiosk/kiosk_browser/browser_widget.py
+++ b/kiosk/kiosk_browser/browser_widget.py
@@ -145,7 +145,7 @@ def _view(self, status):
 
 def user_agent_with_system(user_agent, system_name, system_version):
     """Inject a specific system into a user agent string"""
-    pattern = re.compile('(Mozilla/5.0) \(([^\)]*)\)(.*)')
+    pattern = re.compile(r'(Mozilla/5.0) \(([^\)]*)\)(.*)')
     m = pattern.match(user_agent)
 
     if m == None: