diff --git a/middleware_api/service/oas.py b/middleware_api/service/oas.py
index 71434dbc..a626e95d 100644
--- a/middleware_api/service/oas.py
+++ b/middleware_api/service/oas.py
@@ -36,9 +36,16 @@ def handler(event: dict, context: LambdaContext):
         json_schema = replace_null(json_schema)
         json_schema['info']['version'] = esd_version.split('-')[0]
 
-        json_schema['servers'][0]['url'] = "{ApiGatewayUrl}"
-        json_schema['servers'][0]['variables']['ApiGatewayUrl'][
-            'default'] = "https://xxxxxx.execute-api.ap-northeast-1.amazonaws.com/prod/"
+        json_schema['servers'] = [
+            {
+                "url": "{ApiGatewayUrl}",
+                "variables": {
+                    "ApiGatewayUrl": {
+                        "default": "https://xxxxxx.execute-api.ap-northeast-1.amazonaws.com/prod/"
+                    }
+                }
+            }
+        ]
 
         payload = {
             'isBase64Encoded': False,