diff --git a/src/Symfony/Component/Serializer/Annotation/Groups.php b/src/Symfony/Component/Serializer/Annotation/Groups.php
index 519837a55b73e..b67239bc6f219 100644
--- a/src/Symfony/Component/Serializer/Annotation/Groups.php
+++ b/src/Symfony/Component/Serializer/Annotation/Groups.php
@@ -24,7 +24,7 @@
 class Groups
 {
     /**
-     * @var array
+     * @var string[]
      */
     private $groups;
 
@@ -39,23 +39,20 @@ public function __construct(array $data)
             throw new InvalidArgumentException(sprintf('Parameter of annotation "%s" cannot be empty.', get_class($this)));
         }
 
-        if (!is_array($data['value'])) {
-            throw new InvalidArgumentException(sprintf('Parameter of annotation "%s" must be an array of strings.', get_class($this)));
-        }
-
-        foreach ($data['value'] as $group) {
+        $value = (array) $data['value'];
+        foreach ($value as $group) {
             if (!is_string($group)) {
-                throw new InvalidArgumentException(sprintf('Parameter of annotation "%s" must be an array of strings.', get_class($this)));
+                throw new InvalidArgumentException(sprintf('Parameter of annotation "%s" must be a string or an array of strings.', get_class($this)));
             }
         }
 
-        $this->groups = $data['value'];
+        $this->groups = $value;
     }
 
     /**
      * Gets groups.
      *
-     * @return array
+     * @return string[]
      */
     public function getGroups()
     {
diff --git a/src/Symfony/Component/Serializer/Tests/Annotation/GroupsTest.php b/src/Symfony/Component/Serializer/Tests/Annotation/GroupsTest.php
index 72b877729dc83..8228cc5c98671 100644
--- a/src/Symfony/Component/Serializer/Tests/Annotation/GroupsTest.php
+++ b/src/Symfony/Component/Serializer/Tests/Annotation/GroupsTest.php
@@ -31,7 +31,7 @@ public function testEmptyGroupsParameter()
      */
     public function testNotAnArrayGroupsParameter()
     {
-        new Groups(array('value' => 'coopTilleuls'));
+        new Groups(array('value' => 12));
     }
 
     /**
@@ -49,4 +49,10 @@ public function testGroupsParameters()
         $groups = new Groups(array('value' => $validData));
         $this->assertEquals($validData, $groups->getGroups());
     }
+
+    public function testSingleGroup()
+    {
+        $groups = new Groups(array('value' => 'a'));
+        $this->assertEquals(array('a'), $groups->getGroups());
+    }
 }