diff --git a/src/JMS/Serializer/Handler/DateHandler.php b/src/JMS/Serializer/Handler/DateHandler.php
index 22505816c..68daa7215 100644
--- a/src/JMS/Serializer/Handler/DateHandler.php
+++ b/src/JMS/Serializer/Handler/DateHandler.php
@@ -69,6 +69,11 @@ public function serializeDateTime(VisitorInterface $visitor, \DateTime $date, ar
         if ($visitor instanceof XmlSerializationVisitor && false === $this->xmlCData) {
             return $visitor->visitSimpleString($date->format($this->getFormat($type)), $type, $context);
         }
+
+        $format = $this->getFormat($type);
+        if ('U' === $format) {
+            return $visitor->visitInteger($date->format($format), $type, $context);
+        }
         return $visitor->visitString($date->format($this->getFormat($type)), $type, $context);
     }
 
diff --git a/tests/JMS/Serializer/Tests/Fixtures/Timestamp.php b/tests/JMS/Serializer/Tests/Fixtures/Timestamp.php
new file mode 100755
index 000000000..3facc0413
--- /dev/null
+++ b/tests/JMS/Serializer/Tests/Fixtures/Timestamp.php
@@ -0,0 +1,34 @@
+<?php
+
+/*
+ * Copyright 2013 Johannes M. Schmitt <schmittjoh@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace JMS\Serializer\Tests\Fixtures;
+
+use JMS\Serializer\Annotation\Type;
+
+class Timestamp
+{
+    /**
+     * @Type("DateTime<'U'>")
+     */
+    private $timestamp;
+
+    public function __construct($timestamp)
+    {
+        $this->timestamp = $timestamp;
+    }
+}
diff --git a/tests/JMS/Serializer/Tests/Serializer/BaseSerializationTest.php b/tests/JMS/Serializer/Tests/Serializer/BaseSerializationTest.php
index d3d49bbf1..4dc63ef9e 100644
--- a/tests/JMS/Serializer/Tests/Serializer/BaseSerializationTest.php
+++ b/tests/JMS/Serializer/Tests/Serializer/BaseSerializationTest.php
@@ -29,6 +29,7 @@
 use JMS\Serializer\Tests\Fixtures\Garage;
 use JMS\Serializer\Tests\Fixtures\InlineChildEmpty;
 use JMS\Serializer\Tests\Fixtures\NamedDateTimeArraysObject;
+use JMS\Serializer\Tests\Fixtures\Timestamp;
 use JMS\Serializer\Tests\Fixtures\Tree;
 use JMS\Serializer\Tests\Fixtures\VehicleInterfaceGarage;
 use PhpCollection\Sequence;
@@ -365,6 +366,22 @@ public function getDateTime()
         );
     }
 
+    /**
+     * @dataProvider getTimestamp
+     * @group datetime
+     */
+    public function testTimestamp($key, $value)
+    {
+        $this->assertEquals($this->getContent($key), $this->serialize($value));
+    }
+
+    public function getTimestamp()
+    {
+        return array(
+            array('timestamp', new Timestamp(new \DateTime('2016-02-11 00:00:00', new \DateTimeZone('UTC')))),
+        );
+    }
+
     public function testDateInterval()
     {
         $duration = new \DateInterval('PT45M');
diff --git a/tests/JMS/Serializer/Tests/Serializer/JsonSerializationTest.php b/tests/JMS/Serializer/Tests/Serializer/JsonSerializationTest.php
index dee76d326..5e184e7b7 100644
--- a/tests/JMS/Serializer/Tests/Serializer/JsonSerializationTest.php
+++ b/tests/JMS/Serializer/Tests/Serializer/JsonSerializationTest.php
@@ -89,6 +89,7 @@ protected function getContent($key)
             $outputs['object_when_null'] = '{"text":"foo"}';
             $outputs['object_when_null_and_serialized'] = '{"author":null,"text":"foo"}';
             $outputs['date_time'] = '"2011-08-30T00:00:00+0000"';
+            $outputs['timestamp'] = '{"timestamp":1455148800}';
             $outputs['date_interval'] = '"PT45M"';
             $outputs['car'] = '{"km":5,"type":"car"}';
             $outputs['car_without_type'] = '{"km":5}';
diff --git a/tests/JMS/Serializer/Tests/Serializer/xml/timestamp.xml b/tests/JMS/Serializer/Tests/Serializer/xml/timestamp.xml
new file mode 100755
index 000000000..a9bf077fa
--- /dev/null
+++ b/tests/JMS/Serializer/Tests/Serializer/xml/timestamp.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<result>
+  <timestamp>1455148800</timestamp>
+</result>
diff --git a/tests/JMS/Serializer/Tests/Serializer/yml/timestamp.yml b/tests/JMS/Serializer/Tests/Serializer/yml/timestamp.yml
new file mode 100755
index 000000000..b1c38be9d
--- /dev/null
+++ b/tests/JMS/Serializer/Tests/Serializer/yml/timestamp.yml
@@ -0,0 +1 @@
+timestamp: 1455148800