diff --git a/helpers.js b/helpers.js
index c45d9ee..1715270 100644
--- a/helpers.js
+++ b/helpers.js
@@ -6,7 +6,7 @@ module.exports = function (markers) {
 	function replace(text, marker, getReplacement, once) {
 		var deferred = when.defer();
 		var regExp = new RegExp(markers.prefix + marker + markers.postfix, 'gmi');
-		var matches = text.match(regExp);
+		var matches = text && text.match && text.match(regExp);
 		if (matches) {
 			if (once) {
 				matches = [matches[0]];
diff --git a/preview.js b/preview.js
index 92ea368..730437f 100644
--- a/preview.js
+++ b/preview.js
@@ -252,7 +252,7 @@ module.exports = function (config, mongoDataInstance, helpers, markers) {
 
 	return {
 		getPreviewHTML: getPreviewHTML,
-			_replaceMarkers: replaceMarkers
+		_replaceMarkers: replaceMarkers
 	};
 };
 
diff --git a/test/test.helpers.js b/test/test.helpers.js
new file mode 100644
index 0000000..7a24dff
--- /dev/null
+++ b/test/test.helpers.js
@@ -0,0 +1,29 @@
+var helpers = require('../helpers.js');
+var expect = require('chai').expect;
+var when = require('when');
+
+
+describe('Helpers', function () {
+	var marker_prefix = '<!--\\s*@@';
+	var marker_postfix = '\\s*-->';
+	var helper = helpers({
+		prefix: marker_prefix,
+		postfix: marker_postfix
+	});
+
+	describe('replace', function (done) {
+		it('', function () {
+			var promise = helper.replace(null, null, null, true);
+			expect(promise).to.be.an('object');
+			when(promise).then(
+				function onSuccess(result) {
+					expect(result).to.be.an('object');
+					expect(result).to.be.empty();
+					done();
+				}, function onFailure(err) {
+					done(err);
+				}
+			);
+		})
+	});
+});