diff --git a/web/add/cron/index.php b/web/add/cron/index.php
index f2fd6bf9..b8790ebc 100644
--- a/web/add/cron/index.php
+++ b/web/add/cron/index.php
@@ -16,12 +16,12 @@ top_panel($user,$TAB);
 //if ($_SESSION['user'] == 'admin') {
     if (!empty($_POST['ok'])) {
         // Check input
-        if (empty($_POST['v_min'])) $errors[] = __('minute');
-        if (empty($_POST['v_hour'])) $errors[] = __('hour');
-        if (empty($_POST['v_day'])) $errors[] = __('day');
-        if (empty($_POST['v_month'])) $errors[] = __('month');
-        if (empty($_POST['v_wday'])) $errors[] = __('day of week');
-        if (empty($_POST['v_cmd'])) $errors[] = __('cmd');
+        if (!isset($_POST['v_min'])) $errors[] = __('minute');
+        if (!isset($_POST['v_hour'])) $errors[] = __('hour');
+        if (!isset($_POST['v_day'])) $errors[] = __('day');
+        if (!isset($_POST['v_month'])) $errors[] = __('month');
+        if (!isset($_POST['v_wday'])) $errors[] = __('day of week');
+        if (!isset($_POST['v_cmd'])) $errors[] = __('cmd');
 
         // Protect input
         $v_min = escapeshellarg($_POST['v_min']);
diff --git a/web/templates/admin/edit_cron.html b/web/templates/admin/edit_cron.html
index 9be88c14..45dd5839 100644
--- a/web/templates/admin/edit_cron.html
+++ b/web/templates/admin/edit_cron.html
@@ -52,7 +52,7 @@
                             </tr>
                             <tr>
                                 <td>
-                                    <input type="text" size="20" class="vst-input" name="v_min" <?php if (!empty($v_min)) echo "value=".$v_min; ?>>
+                                    <input type="text" size="20" class="vst-input" name="v_min" <?php if (isset($v_min)) echo "value=".$v_min; ?>>
                                 </td>
                             </tr>
                             <tr>
@@ -62,7 +62,7 @@
                             </tr>
                             <tr>
                                 <td>
-                                    <input type="text" size="20" class="vst-input" name="v_hour" <?php if (!empty($v_hour)) echo "value=".$v_hour; ?>>
+                                    <input type="text" size="20" class="vst-input" name="v_hour" <?php if (isset($v_hour)) echo "value=".$v_hour; ?>>
                                 </td>
                             </tr>
                             <tr>
@@ -72,7 +72,7 @@
                             </tr>
                             <tr>
                                 <td>
-                                    <input type="text" size="20" class="vst-input" name="v_day" <?php if (!empty($v_day)) echo "value=".$v_day; ?>>
+                                    <input type="text" size="20" class="vst-input" name="v_day" <?php if (isset($v_day)) echo "value=".$v_day; ?>>
                                 </td>
                             </tr>
                             <tr>
@@ -82,7 +82,7 @@
                             </tr>
                             <tr>
                                 <td>
-                                    <input type="text" size="20" class="vst-input" name="v_month" <?php if (!empty($v_month)) echo "value=".$v_month; ?>>
+                                    <input type="text" size="20" class="vst-input" name="v_month" <?php if (isset($v_month)) echo "value=".$v_month; ?>>
                                 </td>
                             </tr>
                             <tr>
@@ -92,7 +92,7 @@
                             </tr>
                             <tr>
                                 <td>
-                                    <input type="text" size="20" class="vst-input" name="v_wday" <?php if (!empty($v_wday)) echo "value=".$v_wday; ?>>
+                                    <input type="text" size="20" class="vst-input" name="v_wday" <?php if (isset($v_wday)) echo "value=".$v_wday; ?>>
                                 </td>
                             </tr>
                             <tr>
@@ -102,7 +102,7 @@
                             </tr>
                             <tr>
                                 <td>
-                                    <input type="text" size="20" class="vst-input" name="v_cmd" <?php if (!empty($v_cmd)) echo "value='".$v_cmd."'"; ?>>
+                                    <input type="text" size="20" class="vst-input" name="v_cmd" <?php if (isset($v_cmd)) echo "value='".$v_cmd."'"; ?>>
                                 </td>
                             </tr>
                         </table>