diff --git a/packages/gitbook-plugin-theme-default/src/reducers/sidebar.js b/packages/gitbook-plugin-theme-default/src/reducers/sidebar.js
index 7b4eac644..eef68d408 100644
--- a/packages/gitbook-plugin-theme-default/src/reducers/sidebar.js
+++ b/packages/gitbook-plugin-theme-default/src/reducers/sidebar.js
@@ -1,4 +1,5 @@
-const { Record } = require('immutable');
+const GitBook = require('gitbook-core');
+const { Record } = GitBook.Immutable;
 const ActionTypes = require('../actions/types');
 
 const SidebarState = Record({