diff --git a/web/app.js b/web/app.js
index 40ec6796a..4581cc1e0 100644
--- a/web/app.js
+++ b/web/app.js
@@ -1654,10 +1654,6 @@ function webViewerInitialized() {
     }
   }, true);
 
-  appConfig.sidebar.toggleButton.addEventListener('click', function() {
-    PDFViewerApplication.pdfSidebar.toggle();
-  });
-
   try {
     webViewerOpenFileViaURL(file);
   } catch (reason) {
diff --git a/web/pdf_sidebar.js b/web/pdf_sidebar.js
index 4e2ef24f6..5b39cf5bf 100644
--- a/web/pdf_sidebar.js
+++ b/web/pdf_sidebar.js
@@ -390,6 +390,10 @@ class PDFSidebar {
       }
     });
 
+    this.toggleButton.addEventListener('click', () => {
+      this.toggle();
+    });
+
     // Buttons for switching views.
     this.thumbnailButton.addEventListener('click', () => {
       this.switchView(SidebarView.THUMBS);