diff --git a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/NodeTypes.php b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/NodeTypes.php
index 30a282ae6a..c74df1a906 100644
--- a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/NodeTypes.php
+++ b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/NodeTypes.php
@@ -7,7 +7,6 @@ class NodeTypes
     // Tree node types
     const QUERY               = '#query';
     const GROUP               = '#group';
-    const IN_EXPR             = '#in';
     const AND_EXPR            = '#and';
     const OR_EXPR             = '#or';
     const EXCEPT_EXPR         = '#except';