diff --git a/godoc/static/godocs.js b/godoc/static/godocs.js
index 47d1de92..2ea3c7ad 100644
--- a/godoc/static/godocs.js
+++ b/godoc/static/godocs.js
@@ -248,7 +248,7 @@ function toggleHash() {
 function personalizeInstallInstructions() {
   var prefix = '?download=';
   var s = window.location.search;
-  if (!s.startsWith(prefix)) {
+  if (s.indexOf(prefix) != 0) {
     // No 'download' query string; bail.
     return;
   }
diff --git a/godoc/static/static.go b/godoc/static/static.go
index 3009e246..a75c2c6f 100644
--- a/godoc/static/static.go
+++ b/godoc/static/static.go
@@ -813,7 +813,7 @@ function toggleHash() {
 function personalizeInstallInstructions() {
   var prefix = '?download=';
   var s = window.location.search;
-  if (!s.startsWith(prefix)) {
+  if (s.indexOf(prefix) != 0) {
     // No 'download' query string; bail.
     return;
   }