diff --git a/phpBB/includes/session.php b/phpBB/includes/session.php
index 5f5b39fe27..1dc854caf2 100644
--- a/phpBB/includes/session.php
+++ b/phpBB/includes/session.php
@@ -1966,6 +1966,7 @@ class user extends session
 
 					$key_found = $num;
 				}
+				break;
 			}
 		}
 
diff --git a/tests/user/lang_test.php b/tests/user/lang_test.php
new file mode 100644
index 0000000000..6c60583a7b
--- /dev/null
+++ b/tests/user/lang_test.php
@@ -0,0 +1,58 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+require_once dirname(__FILE__) . '/../../phpBB/includes/session.php';
+
+class phpbb_user_lang_test extends phpbb_test_case
+{
+	public function test_user_lang_sprintf()
+	{
+		$user = new user;
+		$user->lang = array(
+			'FOO'		=> 'BAR',
+			'BARZ'		=> 'PENG',
+			'EMPTY'		=> '',
+			'ZERO'		=> '0',
+			'STR'		=> '%d %s, %d topics',
+			'STR2'		=> '%d foos',
+			'ARRY'		=> array(
+				0		=> 'No posts',		// 0
+				1		=> '1 post',		// 1
+				2		=> '%d posts',		// 2+
+			),
+		);
+
+		// No param
+		$this->assertEquals($user->lang('FOO'), 'BAR');
+		$this->assertEquals($user->lang('EMPTY'), '');
+		$this->assertEquals($user->lang('ZERO'), '0');
+
+		// Invalid index
+		$this->assertEquals($user->lang('VOID'), 'VOID');
+
+		// Unnecessary param
+		$this->assertEquals($user->lang('FOO', 2), 'BAR');
+		$this->assertEquals($user->lang('FOO', 2, 3), 'BAR');
+		$this->assertEquals($user->lang('FOO', 2, 3, 'BARZ'), 'BAR');
+
+		// String
+		$this->assertEquals($user->lang('STR', 24, 'x', 42), '24 x, 42 topics');
+		$this->assertEquals($user->lang('STR2', 64), '64 foos');
+
+		// Array
+		$this->assertEquals($user->lang('ARRY', 0), 'No posts');
+		$this->assertEquals($user->lang('ARRY', 1), '1 post');
+		$this->assertEquals($user->lang('ARRY', 2), '2 posts');
+		$this->assertEquals($user->lang('ARRY', 123), '123 posts');
+
+		// Bug PHPBB3-9949
+		$this->assertEquals($user->lang('ARRY', 1, 2), '1 post');
+		$this->assertEquals($user->lang('ARRY', 1, 's', 2), '1 post');
+	}
+}