diff --git a/Router/DefaultLocaleResolver.php b/Router/DefaultLocaleResolver.php
index 9bb5406..af97776 100755
--- a/Router/DefaultLocaleResolver.php
+++ b/Router/DefaultLocaleResolver.php
@@ -49,7 +49,9 @@ public function resolveLocale(Request $request, array $availableLocales)
         // check if a session exists, and if it contains a locale
         if ($request->hasPreviousSession()) {
             $session = $request->getSession();
-            if ($session->has('_locale')) {
+
+            // Do not use session if not already started
+            if ($session->isStarted() && $session->has('_locale')) {
                 return $session->get('_locale');
             }
         }
@@ -74,4 +76,4 @@ public function resolveLocale(Request $request, array $availableLocales)
 
         return null;
     }
-}
\ No newline at end of file
+}
diff --git a/Tests/Functional/TestBundle/Resources/views/default/index.html.twig b/Tests/Functional/TestBundle/Resources/views/Default/index.html.twig
similarity index 100%
rename from Tests/Functional/TestBundle/Resources/views/default/index.html.twig
rename to Tests/Functional/TestBundle/Resources/views/Default/index.html.twig
diff --git a/Tests/Router/DefaultLocaleResolverTest.php b/Tests/Router/DefaultLocaleResolverTest.php
index 0f17bdb..0fb604c 100755
--- a/Tests/Router/DefaultLocaleResolverTest.php
+++ b/Tests/Router/DefaultLocaleResolverTest.php
@@ -27,26 +27,25 @@ public function getResolutionTests()
         $tests[] = array(Request::create('/?hl=de'), array('foo'), 'de', 'Query parameter is selected');
         $tests[] = array(Request::create('/?hl=de', 'GET', array(), array('hl' => 'en')), array('foo'), 'de', 'Query parameter has precedence before cookie');
 
-        $session = $this->getMock('Symfony\Component\HttpFoundation\Session\SessionInterface');
-        $session->expects($this->any())
-            ->method('has')
-            ->with('_locale')
-            ->will($this->returnValue(true));
-        $session->expects($this->any())
-            ->method('get')
-            ->with('_locale')
-            ->will($this->returnValue('fr'));
-        $session->expects($this->any())
-            ->method('getName')
-            ->will($this->returnValue('SESS'));
-
         $tests[] = array($request = Request::create('/?hl=de', 'GET', array(), array('SESS' => 'foo')), array('foo'), 'de', 'Query parameter has precedence before session');
+        $session = $this->createSession();
         $request->setSession($session);
 
         $tests[] = array($request = Request::create('/', 'GET', array(), array('SESS' => 'foo')), array('foo'), 'fr', 'Session is used');
+        $session = $this->createSession();
+        $request->setSession($session);
+
+        $tests[] = array($request = Request::create('/', 'GET', array(), array('SESS' => 'foo')), array('foo'), null, 'No session');
+
+        $tests[] = array($request = Request::create('/', 'GET', array(), array('SESS' => 'foo')), array('foo'), 'fr', 'Session is not started');
+        $session = $this->createSession();
+        $session->expects($this->any())
+            ->method('isStarted')
+            ->will($this->returnValue(false));
         $request->setSession($session);
 
         $tests[] = array($request = Request::create('/', 'GET', array(), array('hl' => 'es', 'SESS' => 'foo')), array('foo'), 'fr', 'Session has precedence before cookie.');
+        $session = $this->createSession();
         $request->setSession($session);
 
         $tests[] = array(Request::create('/', 'GET', array(), array('hl' => 'es')), array('foo'), 'es', 'Cookie is used');
@@ -65,4 +64,25 @@ protected function setUp()
             'bar' => 'de',
         ));
     }
-}
\ No newline at end of file
+
+    private function createSession()
+    {
+        $session = $this->getMock('Symfony\Component\HttpFoundation\Session\SessionInterface');
+        $session->expects($this->any())
+            ->method('has')
+            ->with('_locale')
+            ->will($this->returnValue(true));
+        $session->expects($this->any())
+            ->method('get')
+            ->with('_locale')
+            ->will($this->returnValue('fr'));
+        $session->expects($this->any())
+            ->method('getName')
+            ->will($this->returnValue('SESS'));
+        $session->expects($this->any())
+            ->method('isStarted')
+            ->will($this->returnValue(true));
+
+        return $session;
+    }
+}