diff --git a/fastapi/utils.py b/fastapi/utils.py
index 4c7350fea..46f2c98c3 100644
--- a/fastapi/utils.py
+++ b/fastapi/utils.py
@@ -180,7 +180,7 @@ def generate_unique_id(route: "APIRoute") -> str:
     operation_id = f"{route.name}{route.path_format}"
     operation_id = re.sub(r"\W", "_", operation_id)
     assert route.methods
-    operation_id = f"{operation_id}_{list(route.methods)[0].lower()}"
+    operation_id = f"{operation_id}_{next(iter(route.methods)).lower()}"
     return operation_id