diff --git a/mongoengine/django/sessions.py b/mongoengine/django/sessions.py
index d1e9289a..9cea0fd8 100644
--- a/mongoengine/django/sessions.py
+++ b/mongoengine/django/sessions.py
@@ -46,7 +46,7 @@ class SessionStore(SessionBase):
         while True:
             self._session_key = self._get_new_session_key()
             try:
-                self.save(must_create=True)
+                self.save(must_create=True, safe=True)
             except CreateError:
                 continue
             self.modified = True