diff --git a/src/module/mb-assets.js b/src/module/mb-assets.js
index ce608f8..ce66a0a 100644
--- a/src/module/mb-assets.js
+++ b/src/module/mb-assets.js
@@ -96,8 +96,11 @@ Hooks.on("renderWallConfig", async (application, element, context, options) => {
   const doc = application.document;
   const scope = "mb-assets";
   const key = "doortile";
-  const defaultValue = null;
-  const value = doc.getFlag(scope, key) ?? defaultValue;
+  const defaultValue = [];
+  let value = doc.getFlag(scope, key) ?? defaultValue;
+  if (value === "null" || value === "undefined") {
+    value = [];
+  }
   const name = `flags.${scope}.${key}`;
   if (options.parts && !options.parts.includes("body")) return;
   const dataField = new foundry.data.fields.DocumentUUIDField({