diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index aa06dd2a9..e13b53095 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -160,8 +160,8 @@ def get_sub_dependant(
     security_requirement = None
     security_scopes = security_scopes or []
     if isinstance(depends, params.Security):
-        dependency_scopes = depends.scopes
-        security_scopes.extend(dependency_scopes)
+        if depends.scopes:
+            security_scopes.extend(depends.scopes)
     if isinstance(dependency, SecurityBase):
         use_scopes: List[str] = []
         if isinstance(dependency, (OAuth2, OpenIdConnect)):