diff --git a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/GlobalStructure.php b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/GlobalStructure.php
index 57f9fba751..451536fea6 100644
--- a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/GlobalStructure.php
+++ b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Structure/GlobalStructure.php
@@ -39,7 +39,7 @@ final class GlobalStructure implements Structure
         return new self($fields, $flags);
     }
 
-    public function __construct(array $fields, array $flags)
+    public function __construct(array $fields = [], array $flags = [])
     {
         Assertion::allIsInstanceOf($fields, Field::class);
         Assertion::allIsInstanceOf($flags, Flag::class);
@@ -51,7 +51,7 @@ final class GlobalStructure implements Structure
         }
     }
 
-    private function add(Field $field)
+    public function add(Field $field)
     {
         $name = $field->getName();
         if (isset($this->fields[$name])) {
diff --git a/tests/Alchemy/Tests/Phrasea/SearchEngine/AST/FlagStatementTest.php b/tests/Alchemy/Tests/Phrasea/SearchEngine/AST/FlagStatementTest.php
index 6a1a2bbbcb..66b86c4ee7 100644
--- a/tests/Alchemy/Tests/Phrasea/SearchEngine/AST/FlagStatementTest.php
+++ b/tests/Alchemy/Tests/Phrasea/SearchEngine/AST/FlagStatementTest.php
@@ -4,6 +4,7 @@ namespace Alchemy\Tests\Phrasea\SearchEngine\AST;
 
 use Alchemy\Phrasea\SearchEngine\Elastic\AST\FlagStatement;
 use Alchemy\Phrasea\SearchEngine\Elastic\Search\QueryContext;
+use Alchemy\Phrasea\SearchEngine\Elastic\Structure\Flag;
 
 /**
  * @group unit
@@ -24,13 +25,14 @@ class FlagStatementTest extends \PHPUnit_Framework_TestCase
     public function testQueryBuild()
     {
         $query_context = $this->prophesize(QueryContext::class);
+        $query_context->getFlag('foo')->willReturn(new Flag('bar'));
 
         $node = new FlagStatement('foo', true);
         $query = $node->buildQuery($query_context->reveal());
 
         $expected = '{
             "term": {
-                "flags.foo": true
+                "flags.bar": true
             }
         }';