diff --git a/src/document/scene-document-validation.ts b/src/document/scene-document-validation.ts
index f04d7b5c..52f272d2 100644
--- a/src/document/scene-document-validation.ts
+++ b/src/document/scene-document-validation.ts
@@ -161,6 +161,13 @@ import {
 } from "../sequencer/project-sequence-steps";
 import { isBundledFoliagePrototypeId } from "../foliage/bundled-foliage-manifest";
 import { isBundledSplineCorridorAssetId } from "../spline-corridor/bundled-spline-corridor-assets";
+import {
+  MATERIAL_TEXTURE_SLOTS,
+  type CustomMaterialDef,
+  type MaterialDef,
+  type MaterialTextureSlot,
+  type StarterMaterialDef
+} from "../materials/starter-material-library";
 import {
   FOLIAGE_PROTOTYPE_LOD_LEVELS,
   isFoliagePrototypeCategory,