diff --git a/chrome/content/zotero/overlay.js b/chrome/content/zotero/overlay.js
index 037e1776c..272a71088 100644
--- a/chrome/content/zotero/overlay.js
+++ b/chrome/content/zotero/overlay.js
@@ -635,7 +635,7 @@ var ZoteroPane = new function()
 			tagSelector.setAttribute('height', maxTS);
 		}
 		
-		height = tagSelector.boxObject.height;
+		var height = tagSelector.boxObject.height;
 		
 		/*
 		Zotero.debug("tagSelector.boxObject.height: " + tagSelector.boxObject.height);