diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 7eeaac17..787a3c36 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -11,3 +11,4 @@ python:
 sphinx:
   builder: html
   fail_on_warning: true
+  configuration: docs/conf.py
diff --git a/src/flask_session/base.py b/src/flask_session/base.py
index 2399b1a3..33616e3e 100644
--- a/src/flask_session/base.py
+++ b/src/flask_session/base.py
@@ -331,7 +331,7 @@ def save_session(
 
     def open_session(self, app: Flask, request: Request) -> ServerSideSession:
         # Get the session ID from the cookie
-        sid = request.cookies.get(app.config["SESSION_COOKIE_NAME"])
+        sid = request.cookies.get(self.get_cookie_name(app))
 
         # If there's no session ID, generate a new one
         if not sid: