diff --git a/core/modules/filters/lookup.js b/core/modules/filters/lookup.js
index 49c8e205a..2174e8c47 100644
--- a/core/modules/filters/lookup.js
+++ b/core/modules/filters/lookup.js
@@ -22,7 +22,7 @@ Export our filter function
 exports.lookup = function(source,operator,options) {
 	var results = [];
 	source(function(tiddler,title) {
-		results.push(options.wiki.getTiddlerText(operator.operand + title) || operator.suffix);
+		results.push(options.wiki.getTiddlerText(operator.operand + title) || operator.suffix || '');
 	});
 	return results;
 };