diff --git a/backup/restorelib.php b/backup/restorelib.php
index 7bb74a4b5ec..8b2d5ca8ed4 100644
--- a/backup/restorelib.php
+++ b/backup/restorelib.php
@@ -810,12 +810,14 @@
                     $user->description = restore_decode_absolute_links(addslashes($user->description));
 
                     //We need to analyse the AUTH field to recode it:
+                    //   - if the field isn't set, we are in a pre 1.4 backup and we'll 
+                    //     use $CFG->auth
                     //   - if the destination site has any kind of INTERNAL authentication, 
                     //     then apply it to the new user.
                     //   - if the destination site has any kind of EXTERNAL authentication, 
                     //     then leave the original authentication of the user.
 
-                    if (is_internal_auth($CFG->auth)) {
+                    if ((! isset($user->auth)) || is_internal_auth($CFG->auth)) {
                         $user->auth = $CFG->auth;
                     }