diff --git a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Thesaurus.php b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Thesaurus.php
index 7abe088520..1acc2c740f 100644
--- a/lib/Alchemy/Phrasea/SearchEngine/Elastic/Thesaurus.php
+++ b/lib/Alchemy/Phrasea/SearchEngine/Elastic/Thesaurus.php
@@ -60,7 +60,7 @@ class Thesaurus
         // TODO Use bulk queries for performance
         $concepts = array();
         foreach ($terms as $index => $term) {
-            $strict = ($term instanceof AST\TermNode);      // a "term" node is [strict group of words]
+            $strict |= ($term instanceof AST\TermNode);      // a "term" node is [strict group of words]
             $concepts[] = $this->findConcepts($term, $lang, $filters[$index], $strict);
         }