diff --git a/www/plugins.FileOpener2.js b/www/plugins.FileOpener2.js
index eb75211..bac1a50 100644
--- a/www/plugins.FileOpener2.js
+++ b/www/plugins.FileOpener2.js
@@ -27,11 +27,13 @@ var exec = require('cordova/exec');
 function FileOpener2() {}
 
 FileOpener2.prototype.open = function (fileName, contentType, callbackContext) {
+    contentType = contentType || ''; 
     callbackContext = callbackContext || {};
     exec(callbackContext.success || null, callbackContext.error || null, 'FileOpener2', 'open', [fileName, contentType]);
 };
 
 FileOpener2.prototype.showOpenWithDialog = function (fileName, contentType, callbackContext) {
+    contentType = contentType || '';
     callbackContext = callbackContext || {};
     exec(callbackContext.success || null, callbackContext.error || null, 'FileOpener2', 'open', [fileName, contentType, false]);
 };