diff --git a/engineioxide/src/futures.rs b/engineioxide/src/futures.rs
index 8cd9cb09..19bd5e61 100644
--- a/engineioxide/src/futures.rs
+++ b/engineioxide/src/futures.rs
@@ -24,6 +24,7 @@ where
 {
     Response::builder()
         .status(code)
+        .header("Content-Type", "text/plain")
         .body(ResponseBody::custom_response(data.into()))
 }