2 files changed, 3 insertions, 3 deletions
diff --git a/toolkit/jetpack/sdk/lang/weak-set.js b/toolkit/jetpack/sdk/lang/weak-set.js
index 8972602a5..0b81a395b 100644
--- a/toolkit/jetpack/sdk/lang/weak-set.js
+++ b/toolkit/jetpack/sdk/lang/weak-set.js
@@ -2,12 +2,12 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+"use strict";
+
 module.metadata = {
   "stability": "experimental"
 };
 
-"use strict";
-
 const { Cu } = require("chrome");
 
 function makeGetterFor(Type) {
diff --git a/toolkit/jetpack/sdk/ui/buttons.js b/toolkit/jetpack/sdk/ui/buttons.js
index 66e0fd742..6aaed3865 100644
--- a/toolkit/jetpack/sdk/ui/buttons.js
+++ b/toolkit/jetpack/sdk/ui/buttons.js
@@ -50,7 +50,7 @@ function insertButton(aWindow, id, onBuild) {
   let toolbar = toolbarId != "" && doc.getElementById(toolbarId);
 
   if (toolbar) {
-    let nextItem = doc.getElementById(nextItemId);
+    let nextItem = nextItemId != "" && doc.getElementById(nextItemId);
     // If nextItem not in toolbar then retrieve it by reading currentset attribute
     if (!(nextItem && nextItem.parentNode && nextItem.parentNode.id == toolbarId)) {
       nextItem = null;