diff --git a/src/contentScripts/communityConsole/batchLock.js b/src/contentScripts/communityConsole/batchLock.js
index 83af3ce..29a3dc3 100644
--- a/src/contentScripts/communityConsole/batchLock.js
+++ b/src/contentScripts/communityConsole/batchLock.js
@@ -3,13 +3,14 @@
 import {addButtonToThreadListActions, removeChildNodes, shouldAddBtnToActionBar, softRefreshView} from './utils/common.js';
 
 const kLockDebugId = 'twpt-lock';
+export const kModalPaneSelector = '.pane[pane-id="default--1"]';
 
 export var batchLock = {
   shouldAddButton(node) {
     return shouldAddBtnToActionBar(kLockDebugId, node);
   },
   createDialog() {
-    var modal = document.querySelector('.pane[pane-id="default-1"]');
+    var modal = document.querySelector(kModalPaneSelector);
 
     var dialog = document.createElement('material-dialog');
     dialog.setAttribute('role', 'dialog');
diff --git a/src/contentScripts/communityConsole/utils/common.js b/src/contentScripts/communityConsole/utils/common.js
index e1d417b..3d2bac5 100644
--- a/src/contentScripts/communityConsole/utils/common.js
+++ b/src/contentScripts/communityConsole/utils/common.js
@@ -3,7 +3,7 @@
 import {createPlainTooltip} from '../../../common/tooltip.js';
 
 export function removeChildNodes(node) {
-  while (node.firstChild) {
+  while (node?.firstChild) {
     node.removeChild(node.firstChild);
   }
 }
diff --git a/src/injections/batchLock.js b/src/injections/batchLock.js
index 6d7a1e5..20bea13 100644
--- a/src/injections/batchLock.js
+++ b/src/injections/batchLock.js
@@ -1,6 +1,7 @@
 import {CCApi} from '../common/api.js';
 import {parseUrl, recursiveParentElement} from '../common/commonUtils.js';
 import {getAuthUser} from '../common/communityConsoleUtils.js';
+import {kModalPaneSelector} from '../contentScripts/communityConsole/batchLock.js';
 
 // Source:
 // https://stackoverflow.com/questions/33063774/communication-from-an-injected-script-to-the-content-script-with-a-response
@@ -34,8 +35,9 @@
 })();
 
 function enableEndButtons() {
-  var buttons = document.querySelectorAll(
-      '.pane[pane-id="default-1"] footer[data-footer-id="1"] material-button');
+  var buttons =
+      document.querySelector(kModalPaneSelector)
+          .querySelectorAll('footer[data-footer-id="1"] material-button');
   buttons.forEach(btn => {
     btn.classList.remove('is-disabled');
   });
@@ -74,7 +76,7 @@
 }
 
 function lockThreads(action) {
-  var modal = document.querySelector('.pane[pane-id="default-1"]');
+  var modal = document.querySelector(kModalPaneSelector);
   modal.querySelector('footer[data-footer-id="0"]').classList.add('is-hidden');
   modal.querySelector('footer[data-footer-id="1"]')
       .classList.remove('is-hidden');