diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index 551357f90..ce6a05184 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -2252,13 +2252,15 @@ async def oauth_callback(provider: str, request: Request, response: Response):
             role = "admin"
         elif webui_app.state.config.ENABLE_OAUTH_ROLE_MAPPING:
             oauth_claim = webui_app.state.config.OAUTH_ROLES_CLAIM
-            oauth_roles = user_data.get(oauth_claim) # Works for simple claims with no nesting
+            oauth_roles = user_data.get(oauth_claim)  # Works for simple claims with no nesting
             if oauth_roles and "." in oauth_claim:
                 # Implementation to handle nested claims of arbitrary depth
                 nested_claims = oauth_claim.split(".")
-                claim_data = user_data.get(nested_claims[0])
-                for nested_claim in nested_claims[1:]:
+                claim_data = user_data
+                for nested_claim in nested_claims:
                     claim_data = claim_data.get(nested_claim)
+                    if claim_data is None:
+                        break
                 oauth_roles = claim_data
 
             log.info(f"User {user.name} has OAuth roles: {oauth_roles}")