diff --git a/app/Scopes/LdapFilterScope.php b/app/Scopes/LdapFilterScope.php
index d1f9dc4e38..5442229edb 100644
--- a/app/Scopes/LdapFilterScope.php
+++ b/app/Scopes/LdapFilterScope.php
@@ -13,8 +13,8 @@ class LdapFilterScope implements ScopeInterface {
      */
     public function apply(Builder $query)
     {
-        $filter = config('ldap_auth.custom_filter');
-        if ( $filter ) {
+        $filter = (string) config('ldap_auth.custom_filter');
+        if ( '' !== $filter ) {
             $query->rawFilter($filter);
         }
     }