diff --git a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/QueryCompiler.php b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/QueryCompiler.php
index 7920326f54..7fa7fd60d2 100644
--- a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/QueryCompiler.php
+++ b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Search/QueryCompiler.php
@@ -38,6 +38,8 @@ class QueryCompiler
 
     private function injectThesaurusConcepts(Query $query)
     {
+        // TODO We must restrict thesaurus matching for IN queries, and only
+        // search in each field's root concepts.
         $nodes = $query->getTermNodes();
         $concepts = $this->thesaurus->findConceptsBulk($nodes);