diff --git a/addons/base/static/src/js/dates.js b/addons/base/static/src/js/dates.js
index a243130aab2..8daea39773f 100644
--- a/addons/base/static/src/js/dates.js
+++ b/addons/base/static/src/js/dates.js
@@ -96,7 +96,7 @@ var fts = function(str, size) {
  * @returns {String} A string representing a datetime.
  */
 openerp.base.format_datetime = function(obj) {
-    if(! str) {
+    if (!obj) {
         return false;
     }
     return fts(obj.getUTCFullYear(),4) + "-" + fts(obj.getUTCMonth() + 1,2) + "-"
@@ -112,7 +112,7 @@ openerp.base.format_datetime = function(obj) {
  * @returns {String} A string representing a date.
  */
 openerp.base.format_date = function(obj) {
-    if(! str) {
+    if (!obj) {
         return false;
     }
     return fts(obj.getFullYear(),4) + "-" + fts(obj.getMonth() + 1,2) + "-"
@@ -127,11 +127,11 @@ openerp.base.format_date = function(obj) {
  * @returns {String} A string representing a time.
  */
 openerp.base.format_time = function(obj) {
-    if(! str) {
+    if (!obj) {
         return false;
     }
     return fts(obj.getHours(),2) + ":" + fts(obj.getMinutes(),2) + ":"
         + fts(obj.getSeconds(),2);
 };
     
-};
\ No newline at end of file
+};