diff --git a/app/static/client.js b/app/static/client.js
index 84c2c9541..dac54894c 100644
--- a/app/static/client.js
+++ b/app/static/client.js
@@ -1,4 +1,6 @@
-var el = x => document.getElementById(x);
+function el(x) {
+  return document.getElementById(x);
+}
 
 function showPicker() {
   el("file-input").click();