diff --git a/src/net/http/roundtrip_js.go b/src/net/http/roundtrip_js.go
index 336c413cea23c8..cb4a4392b51985 100644
--- a/src/net/http/roundtrip_js.go
+++ b/src/net/http/roundtrip_js.go
@@ -60,7 +60,9 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 			return nil, err
 		}
 		req.Body.Close()
-		opt.Set("body", body)
+		a := js.TypedArrayOf(body)
+		defer a.Release()
+		opt.Set("body", a)
 	}
 	respPromise := js.Global().Call("fetch", req.URL.String(), opt)
 	var (