diff --git a/src/Ilios/MeSH/Model/Descriptor.php b/src/Ilios/MeSH/Model/Descriptor.php
index 0b299e1..28f1834 100644
--- a/src/Ilios/MeSH/Model/Descriptor.php
+++ b/src/Ilios/MeSH/Model/Descriptor.php
@@ -30,7 +30,7 @@ class Descriptor extends Reference
 
     protected ?string $onlineNote = null;
 
-    protected ?string $publicMeshNote;
+    protected ?string $publicMeshNote = null;
 
     protected array $previousIndexing = [];