diff --git a/library/src/middleware/req_ctx.rs b/library/src/middleware/req_ctx.rs
index 2574f05..e2faf89 100644
--- a/library/src/middleware/req_ctx.rs
+++ b/library/src/middleware/req_ctx.rs
@@ -42,7 +42,7 @@ pub async fn authenticate_ctx(mut req: Request, next: Next) -> Response {
             if value_str.is_empty() {
                 String::from("zh-CN")
             } else {
-                String::from(value_str[1])
+                String::from(value_str[0])
             }
         },
         None => String::from("zh-CN"),