diff --git a/chrome/content/zotero/xpcom/search.js b/chrome/content/zotero/xpcom/search.js
index 8cf11642a..f8c85c976 100644
--- a/chrome/content/zotero/xpcom/search.js
+++ b/chrome/content/zotero/xpcom/search.js
@@ -2246,7 +2246,7 @@ Zotero.SearchConditions = new function(){
 		
 		for (var i in parts) {
 			var part = parts[i];
-			if (!part.length) {
+			if (!part || !part.length) {
 				continue;
 			}