diff --git a/browser/base/content/tabbrowser.xml b/browser/base/content/tabbrowser.xml
index 81bf63573692..1e5695d0c1c0 100644
--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -1830,7 +1830,7 @@
             var isInToolbox = target == this._cachedTargetInToolbox;
             while (target && !isInToolbox) {
               if (target == gNavToolbox) {
-                goolbox = true;
+                isInToolbox = true;
                 this._cachedTargetInToolbox = target;
               }
               else