diff --git a/plugins/libcalendaring/libcalendaring.js b/plugins/libcalendaring/libcalendaring.js
index bdb2f1d0..931943dd 100644
--- a/plugins/libcalendaring/libcalendaring.js
+++ b/plugins/libcalendaring/libcalendaring.js
@@ -337,9 +337,9 @@ function rcube_libcalendaring(settings)
             $(this).parent().find('span.edit-alarm-values')[(this.selectedIndex>0?'show':'hide')]();
         });
         $(prefix+' select.edit-alarm-offset').change(function(){
-            var mode = $(this).val() == '@' ? 'show' : 'hide';
-            $(this).parent().find('.edit-alarm-date, .edit-alarm-time')[mode]();
-            $(this).parent().find('.edit-alarm-value').prop('disabled', mode == 'show');
+            var val = $(this).val();
+            $(this).parent().find('.edit-alarm-date, .edit-alarm-time')[val == '@' ? 'show' : 'hide']();
+            $(this).parent().find('.edit-alarm-value').prop('disabled', val === '@' || val === '0');
         });
 
         $(prefix+' .edit-alarm-date').removeClass('hasDatepicker').removeAttr('id').datepicker(datepicker_settings);
@@ -397,6 +397,10 @@ function rcube_libcalendaring(settings)
               $('input.edit-alarm-date', domnode).val(this.format_datetime(ondate, 1));
               $('input.edit-alarm-time', domnode).val(this.format_datetime(ondate, 2));
           }
+          else if (String(alarm.trigger).match(/^[-+]*0[MHDS]$/)) {
+              $('input.edit-alarm-value', domnode).val('0');
+              $('select.edit-alarm-offset', domnode).val('0');
+          }
           else if (String(alarm.trigger).match(/([-+])(\d+)([MHDS])/)) {
               val = RegExp.$2; offset = ''+RegExp.$1+RegExp.$3;
               $('input.edit-alarm-value', domnode).val(val);
@@ -419,6 +423,9 @@ function rcube_libcalendaring(settings)
                 if (offset == '@') {
                     alarm.trigger = '@' + me.date2unixtime(me.parse_datetime($('input.edit-alarm-time', elem).val(), $('input.edit-alarm-date', elem).val()));
                 }
+                else if (offset === '0') {
+                    alarm.trigger = '0S';
+                }
                 else if (!isNaN((val = parseInt($('input.edit-alarm-value', elem).val()))) && val >= 0) {
                     alarm.trigger = offset[0] + val + offset[1];
                 }
diff --git a/plugins/libcalendaring/libcalendaring.php b/plugins/libcalendaring/libcalendaring.php
index fc5ba325..f3b7cd6c 100644
--- a/plugins/libcalendaring/libcalendaring.php
+++ b/plugins/libcalendaring/libcalendaring.php
@@ -324,19 +324,21 @@ class libcalendaring extends rcube_plugin
     public function alarm_select($attrib, $alarm_types, $absolute_time = true)
     {
         unset($attrib['name']);
-        $select_type = new html_select(array('name' => 'alarmtype[]', 'class' => 'edit-alarm-type', 'id' => $attrib['id']));
+
+        $input_value = new html_inputfield(array('name' => 'alarmvalue[]', 'class' => 'edit-alarm-value', 'size' => 3));
+        $input_date  = new html_inputfield(array('name' => 'alarmdate[]', 'class' => 'edit-alarm-date', 'size' => 10));
+        $input_time  = new html_inputfield(array('name' => 'alarmtime[]', 'class' => 'edit-alarm-time', 'size' => 6));
+        $select_type   = new html_select(array('name' => 'alarmtype[]', 'class' => 'edit-alarm-type', 'id' => $attrib['id']));
+        $select_offset = new html_select(array('name' => 'alarmoffset[]', 'class' => 'edit-alarm-offset'));
+
         $select_type->add($this->gettext('none'), '');
         foreach ($alarm_types as $type)
             $select_type->add($this->gettext(strtolower("alarm{$type}option")), $type);
 
-        $input_value = new html_inputfield(array('name' => 'alarmvalue[]', 'class' => 'edit-alarm-value', 'size' => 3));
-        $input_date = new html_inputfield(array('name' => 'alarmdate[]', 'class' => 'edit-alarm-date', 'size' => 10));
-        $input_time = new html_inputfield(array('name' => 'alarmtime[]', 'class' => 'edit-alarm-time', 'size' => 6));
-
-        $select_offset = new html_select(array('name' => 'alarmoffset[]', 'class' => 'edit-alarm-offset'));
         foreach (array('-M','-H','-D','+M','+H','+D') as $trigger)
             $select_offset->add($this->gettext('trigger' . $trigger), $trigger);
 
+        $select_offset->add($this->gettext('trigger0'), '0');
         if ($absolute_time)
             $select_offset->add($this->gettext('trigger@'), '@');
 
diff --git a/plugins/libcalendaring/localization/en_US.inc b/plugins/libcalendaring/localization/en_US.inc
index e5e04261..00a01f5b 100644
--- a/plugins/libcalendaring/localization/en_US.inc
+++ b/plugins/libcalendaring/localization/en_US.inc
@@ -29,6 +29,7 @@ $labels['trigger-D'] = 'days before';
 $labels['trigger+M'] = 'minutes after';
 $labels['trigger+H'] = 'hours after';
 $labels['trigger+D'] = 'days after';
+$labels['trigger0'] = 'on time';
 $labels['triggerattime'] = 'at time';
 $labels['addalarm'] = 'Add alarm';
 $labels['removealarm'] = 'Remove alarm';