diff --git a/setup/class_setupStep_Migrate.inc b/setup/class_setupStep_Migrate.inc
index 399ec92e309e5aa12adb1f27ffa808ac0e1549e3..de24e6cc175c3dbd5c9d8d4cde9a68c813aa9274 100644
--- a/setup/class_setupStep_Migrate.inc
+++ b/setup/class_setupStep_Migrate.inc
@@ -264,7 +264,7 @@ class Step_Migrate extends setupStep
       'outsideGroups' => new StepMigrateCheck($this, 'outsideGroups', _('Checking for groups outside the groups tree')),
       'orgUnits'      => new StepMigrateCheck($this, 'orgUnits',      _('Checking for invisible departments')),
       'uidNumber'     => new StepMigrateCheck($this, 'uidNumber',     _('Checking for duplicated UID numbers')),
-      'gidNumber'     => new StepMigrateCheck($this, 'gidNumber',     _('Checking for duplicate GID numbers')),
+      'gidNumber'     => new StepMigrateCheck($this, 'gidNumber',     _('Checking for duplicated GID numbers')),
     );
 
     $this->checks = $checks;
@@ -1362,15 +1362,20 @@ class Step_Migrate extends setupStep
     foreach ($tmp as $entries) {
       if (count($entries) > 1) {
         foreach ($entries as $entry) {
-          $this->check_uidNumbers[base64_encode($entry['dn'])] = $entry;
+          $this->check_uidNumbers[$entry['dn']] = $entry;
         }
       }
     }
 
     if ($this->check_uidNumbers) {
+      $list = '<ul>';
+      foreach ($this->check_uidNumbers as $dn => $entry) {
+        $list .= '<li>'.$dn.' ('.$entry['uidNumber'][0].')</li>';
+      }
+      $list .= '</ul>';
       throw new CheckFailedException(
         "<div style='color:#F0A500'>"._("Warning")."</div>",
-        sprintf(_('Found %s duplicate values for attribute "uidNumber".'), count($this->check_uidNumbers))
+        sprintf(_('Found %s duplicate values for attribute "uidNumber":%s'), count($this->check_uidNumbers), $list)
       );
     } else {
       return '';
@@ -1401,15 +1406,20 @@ class Step_Migrate extends setupStep
     foreach ($tmp as $entries) {
       if (count($entries) > 1) {
         foreach ($entries as $entry) {
-          $this->check_gidNumbers[base64_encode($entry['dn'])] = $entry;
+          $this->check_gidNumbers[$entry['dn']] = $entry;
         }
       }
     }
 
     if ($this->check_gidNumbers) {
+      $list = '<ul>';
+      foreach ($this->check_gidNumbers as $dn => $entry) {
+        $list .= '<li>'.$dn.' ('.$entry['gidNumber'][0].')</li>';
+      }
+      $list .= '</ul>';
       throw new CheckFailedException(
         "<div style='color:#F0A500'>"._("Warning")."</div>",
-        sprintf(_('Found %s duplicate values for attribute "gidNumber".'), count($this->check_gidNumbers))
+        sprintf(_('Found %s duplicate values for attribute "gidNumber":%s'), count($this->check_gidNumbers), $list)
       );
     } else {
       return '';