diff --git a/defaults/preferences/treestyletab.js b/defaults/preferences/treestyletab.js
index 5b5e68b4..237bb31a 100644
--- a/defaults/preferences/treestyletab.js
+++ b/defaults/preferences/treestyletab.js
@@ -37,7 +37,7 @@ pref("extensions.treestyletab.tabbar.autoShow.feedback", false);
 pref("extensions.treestyletab.tabbar.autoShow.feedback.delay", 3000);
 pref("extensions.treestyletab.tabbar.autoShow.keepShownOnMouseover", true);
 pref("extensions.treestyletab.tabbar.togglerSize", 5);
-pref("extensions.treestyletab.tabbar.fixed.horizontal", true);
+pref("extensions.treestyletab.tabbar.fixed.horizontal", false);
 pref("extensions.treestyletab.tabbar.fixed.vertical", false);
 pref("extensions.treestyletab.tabbar.syncRelatedPrefsForDynamicPosition", true);
 pref("extensions.treestyletab.enableSubtreeIndent.horizontal", false);