diff --git a/fastapi_gateway_auto_generate/domain/usecases/BuildRoutesUsecase.py b/fastapi_gateway_auto_generate/domain/usecases/BuildRoutesUsecase.py
index 3fe04e5..9e5a514 100644
--- a/fastapi_gateway_auto_generate/domain/usecases/BuildRoutesUsecase.py
+++ b/fastapi_gateway_auto_generate/domain/usecases/BuildRoutesUsecase.py
@@ -132,7 +132,7 @@ def sort_elements_by_value(arguments):
                 argument["type"] = param_type
 
                 if not route_model.query_required[i]:
-                    argument["value"] = default_values[query]
+                    argument["value"] = default_values.get(query, None)
                     argument["type"] = f"{param_type} | None"
 
                 if route_model.query_is_cookie[i]: