diff --git a/lib/user/database.php b/lib/user/database.php
index a4cffe5d0c10e1ab7012e1d77e8bf177b9cc5139..dc11614cc57acf1ad998b781c88f1bf2f2581c36 100644
--- a/lib/user/database.php
+++ b/lib/user/database.php
@@ -121,7 +121,7 @@ class OC_User_Database extends OC_User_Backend {
 	 * returns the user id or false
 	 */
 	public function checkPassword( $uid, $password ){
-		$query = OC_DB::prepare( 'SELECT `uid`, `password` FROM `*PREFIX*users` WHERE `uid` = ?' );
+		$query = OC_DB::prepare( 'SELECT `uid`, `password` FROM `*PREFIX*users` WHERE LOWER(`uid`) = LOWER(?)' );
 		$result = $query->execute( array( $uid));
 
 		$row=$result->fetchRow();
@@ -170,7 +170,7 @@ class OC_User_Database extends OC_User_Backend {
 	 * @return boolean
 	 */
 	public function userExists($uid){
-		$query = OC_DB::prepare( 'SELECT * FROM `*PREFIX*users` WHERE `uid` = ?' );
+		$query = OC_DB::prepare( 'SELECT * FROM `*PREFIX*users` WHERE LOWER(`uid`) = LOWER(?)' );
 		$result = $query->execute( array( $uid ));
 		
 		return $result->numRows() > 0;