diff --git a/auth/ldap/lib.php b/auth/ldap/lib.php
index b0eb9e4..f5c7b47 100644
--- a/auth/ldap/lib.php
+++ b/auth/ldap/lib.php
@@ -1000,6 +1000,22 @@ function auth_user_update_password($user
                           . ldap_err2str(ldap_errno($ldapconnection)));
             }    
             break;
+        case 'ad':
+            // Passwords in Active Directory must be encoded as Unicode
+            // strings (UCS-2 Little Endian format) and surrounded with
+            // double quotes. See http://support.microsoft.com/?kbid=269190
+            if (!function_exists('mb_convert_encoding')) {
+                error_log ('You need the mbstring extension to change passwords in Active Directory');
+                return false;
+            }
+            $newpassword = mb_convert_encoding('"'.$newpassword.'"', "UCS-2LE", "auto");
+            $result = ldap_modify($ldapconnection, $user_dn, array('unicodePwd' => $newpassword));
+            if(!$result){
+                error_log('LDAP Error in auth_user_update_password(). Error code: ' 
+                          . ldap_errno($ldapconnection) . '; Error string : '
+                          . ldap_err2str(ldap_errno($ldapconnection)));
+            }
+            break;
         default:
             $usedconnection = &$ldapconnection;
             // send ldap the password in cleartext, it will md5 it itself