diff --git a/jupyter_server/auth/login.py b/jupyter_server/auth/login.py
index b31168ecc0..7df56918e0 100644
--- a/jupyter_server/auth/login.py
+++ b/jupyter_server/auth/login.py
@@ -109,7 +109,7 @@ def set_login_cookie(cls, handler, user_id=None):
         handler.set_secure_cookie(handler.cookie_name, user_id, **cookie_options)
         return user_id
 
-    auth_header_pat = re.compile("token\s+(.+)", re.IGNORECASE)
+    auth_header_pat = re.compile(r"token\s+(.+)", re.IGNORECASE)
 
     @classmethod
     def get_token(cls, handler):