diff --git a/change_log.txt b/change_log.txt
index a52d5236e..cc7fede20 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -2,7 +2,9 @@
 11.10.2018
  - bugfix {insert} not works when caching is enabled and included template is present
    https://github.com/smarty-php/smarty/issues/496
-   
+ - bugfix in date-format modifier; NULL at date string or default_date did not produce correct output
+   https://github.com/smarty-php/smarty/pull/458
+
 09.10.2018
  - bugfix fix of 26.8.2017 https://github.com/smarty-php/smarty/issues/327
    modifier is applied to sum expression https://github.com/smarty-php/smarty/issues/491
diff --git a/libs/Smarty.class.php b/libs/Smarty.class.php
index a3d624863..2565d3f64 100644
--- a/libs/Smarty.class.php
+++ b/libs/Smarty.class.php
@@ -112,7 +112,7 @@ class Smarty extends Smarty_Internal_TemplateBase
     /**
      * smarty version
      */
-    const SMARTY_VERSION = '3.1.34-dev-3';
+    const SMARTY_VERSION = '3.1.34-dev-4';
     /**
      * define variable scopes
      */
diff --git a/libs/plugins/modifier.date_format.php b/libs/plugins/modifier.date_format.php
index 23b69430b..c8e88c5c9 100644
--- a/libs/plugins/modifier.date_format.php
+++ b/libs/plugins/modifier.date_format.php
@@ -41,9 +41,9 @@ function smarty_modifier_date_format($string, $format = null, $default_date = ''
         }
         $is_loaded = true;
     }
-    if ($string !== '' && $string !== '0000-00-00' && $string !== '0000-00-00 00:00:00') {
+    if (!empty($string) && $string !== '0000-00-00' && $string !== '0000-00-00 00:00:00') {
         $timestamp = smarty_make_timestamp($string);
-    } elseif ($default_date !== '') {
+    } elseif (!empty($default_date)) {
         $timestamp = smarty_make_timestamp($default_date);
     } else {
         return;