diff --git a/controllers/customJavascript.go b/controllers/customJavascript.go
index f20dfdf25..dc6cf17a9 100644
--- a/controllers/customJavascript.go
+++ b/controllers/customJavascript.go
@@ -8,6 +8,8 @@ import (
 
 // ServeCustomJavascript will serve optional custom Javascript.
 func ServeCustomJavascript(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/javascript; charset=utf-8")
+
 	js := data.GetCustomJavascript()
 	_, _ = w.Write([]byte(js))
 }