diff --git a/app/code/core/Mage/Admin/Model/User.php b/app/code/core/Mage/Admin/Model/User.php
index 5d5107adb3575..69394d7769940 100644
--- a/app/code/core/Mage/Admin/Model/User.php
+++ b/app/code/core/Mage/Admin/Model/User.php
@@ -384,7 +384,11 @@ public function reload()
      */
     public function loadByUsername($username)
     {
-        $this->setData($this->getResource()->loadByUsername($username));
+        $user = $this->getResource()->loadByUsername($username);
+        if ($user) {
+            $this->setData($user);
+        }
+
         return $this;
     }
 
diff --git a/dev/tests/integration/testsuite/Mage/Admin/Model/UserTest.php b/dev/tests/integration/testsuite/Mage/Admin/Model/UserTest.php
new file mode 100644
index 0000000000000..f8fdb303d8a0d
--- /dev/null
+++ b/dev/tests/integration/testsuite/Mage/Admin/Model/UserTest.php
@@ -0,0 +1,56 @@
+<?php
+/**
+ * Magento
+ *
+ * NOTICE OF LICENSE
+ *
+ * This source file is subject to the Open Software License (OSL 3.0)
+ * that is bundled with this package in the file LICENSE.txt.
+ * It is also available through the world-wide-web at this URL:
+ * http://opensource.org/licenses/osl-3.0.php
+ * If you did not receive a copy of the license and are unable to
+ * obtain it through the world-wide-web, please send an email
+ * to license@magentocommerce.com so we can send you a copy immediately.
+ *
+ * DISCLAIMER
+ *
+ * Do not edit or add to this file if you wish to upgrade Magento to newer
+ * versions in the future. If you wish to customize Magento for your
+ * needs please refer to http://www.magentocommerce.com for more information.
+ *
+ * @category    Magento
+ * @package     Magento_Admin
+ * @subpackage  integration_tests
+ * @copyright   Copyright (c) 2011 Magento Inc. (http://www.magentocommerce.com)
+ * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
+ */
+
+/**
+ * Tests admin user model:
+ * - general behaviour is tested
+ *
+ * @group module:Mage_Admin
+ * @magentoDataFixture Mage/Admin/_files/user.php
+ */
+class Mage_Admin_Model_UserTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @var Mage_Admin_Model_User
+     */
+    protected $_model;
+
+    protected function setUp()
+    {
+        $this->_model = new Mage_Admin_Model_User;
+    }
+
+    /**
+     * Ensure that an exception is not thrown if the user does not exist
+     */
+    public function testloadByUsername() {
+        $this->_model->loadByUsername('non_exiting_user');
+        $this->assertNull($this->_model->getId(), 'The admin user has an unexpected ID');
+        $this->_model->loadByUsername('adminuser');
+        $this->assertTrue(!is_null($this->_model->getId()), 'The admin user should have been loaded');
+    }
+}
diff --git a/dev/tests/integration/testsuite/Mage/Admin/_files/user.php b/dev/tests/integration/testsuite/Mage/Admin/_files/user.php
new file mode 100644
index 0000000000000..363ab0871a5d3
--- /dev/null
+++ b/dev/tests/integration/testsuite/Mage/Admin/_files/user.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ * Magento
+ *
+ * NOTICE OF LICENSE
+ *
+ * This source file is subject to the Open Software License (OSL 3.0)
+ * that is bundled with this package in the file LICENSE.txt.
+ * It is also available through the world-wide-web at this URL:
+ * http://opensource.org/licenses/osl-3.0.php
+ * If you did not receive a copy of the license and are unable to
+ * obtain it through the world-wide-web, please send an email
+ * to license@magentocommerce.com so we can send you a copy immediately.
+ *
+ * DISCLAIMER
+ *
+ * Do not edit or add to this file if you wish to upgrade Magento to newer
+ * versions in the future. If you wish to customize Magento for your
+ * needs please refer to http://www.magentocommerce.com for more information.
+ *
+ * @category    Magento
+ * @package     Mage_Admin
+ * @subpackage  integration_tests
+ * @copyright   Copyright (c) 2011 Magento Inc. (http://www.magentocommerce.com)
+ * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
+ */
+
+$product = new Mage_Admin_Model_User();
+$product->setFirstname('Admin')
+    ->setLastname('User')
+    ->setEmail('test@magento.com')
+    ->setUsername('adminuser')
+    ->setPassword('1234567890')
+    ->setIsActive(1)
+    ->save();