diff --git a/starbot/utils/network.py b/starbot/utils/network.py
index 4939de1..a8084f6 100644
--- a/starbot/utils/network.py
+++ b/starbot/utils/network.py
@@ -134,7 +134,7 @@ async def request(method: str,
                 content_type = resp.headers.get("content-type")
 
                 # 不是 application/json
-                if content_type.lower().index("application/json") == -1:
+                if content_type.lower().find("application/json") == -1:
                     raise ResponseException("响应不是 application/json 类型")
 
                 raw_data = await resp.text()