diff --git a/IndexManager.php b/IndexManager.php
index b117847..5fc30f9 100644
--- a/IndexManager.php
+++ b/IndexManager.php
@@ -13,7 +13,7 @@ class IndexManager
      * @param array  $indexesByName
      * @param string $defaultIndexName
      */
-    public function __construct(array $indexesByName, $defaultIndex)
+    public function __construct(array $indexesByName, \Elastica_Index $defaultIndex)
     {
         $this->indexesByName = $indexesByName;
         $this->defaultIndexName = $defaultIndex->getName();
diff --git a/Tests/IndexManagerTest.php b/Tests/IndexManagerTest.php
index 1eec086..63e6ded 100644
--- a/Tests/IndexManagerTest.php
+++ b/Tests/IndexManagerTest.php
@@ -17,7 +17,16 @@ class IndexManagerTest extends \PHPUnit_Framework_TestCase
             'index1' => 'test1',
             'index2' => 'test2',
         );
-        $this->indexManager = new IndexManager($this->indexesByName, $this->defaultIndexName);
+
+        $defaultIndex = $this->getMockBuilder('Elastica_Index')
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        $defaultIndex->expects($this->any())
+            ->method('getName')
+            ->will($this->returnValue($this->defaultIndexName));
+
+        $this->indexManager = new IndexManager($this->indexesByName, $defaultIndex);
     }
 
     public function testGetAllIndexes()