diff --git a/app/assets/javascripts/discourse/components/topic-progress.js.es6 b/app/assets/javascripts/discourse/components/topic-progress.js.es6
index 66351564a54..243d45625cd 100644
--- a/app/assets/javascripts/discourse/components/topic-progress.js.es6
+++ b/app/assets/javascripts/discourse/components/topic-progress.js.es6
@@ -162,7 +162,7 @@ export default Ember.Component.extend({
     const windowHeight = $(window).height();
     const composerHeight = $("#reply-control").height() || 0;
     const isDocked = offset >= maximumOffset - windowHeight + composerHeight;
-    const bottom = $("#main").height() - maximumOffset;
+    const bottom = $("body").height() - maximumOffset;
 
     if (composerHeight > 0) {
       $wrapper.css("bottom", isDocked ? bottom : composerHeight);