diff --git a/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart b/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart
index ce5423ef..558fb195 100644
--- a/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart
+++ b/thermion_dart/lib/src/filament/src/implementation/ffi_filament_app.dart
@@ -557,6 +557,15 @@ class FFIFilamentApp extends FilamentApp<Pointer> {
     return instance;
   }
 
+  ///
+  ///
+  ///
+  Future setMaterialInstanceAt(ThermionEntity entity, int index,
+      MaterialInstance materialInstance) async {
+    RenderableManager_setMaterialInstanceAt(renderableManager, entity, index,
+        (materialInstance as FFIMaterialInstance).pointer);
+  }
+
   ///
   ///
   ///
diff --git a/thermion_dart/lib/src/filament/src/interface/filament_app.dart b/thermion_dart/lib/src/filament/src/interface/filament_app.dart
index 13fda1be..95f1fad2 100644
--- a/thermion_dart/lib/src/filament/src/interface/filament_app.dart
+++ b/thermion_dart/lib/src/filament/src/interface/filament_app.dart
@@ -196,7 +196,13 @@ abstract class FilamentApp<T> {
   ///
   ///
   Future<MaterialInstance> getMaterialInstanceAt(
-      ThermionEntity entity, int index);
+      ThermionEntity entity, int primitiveIndex);
+
+  ///
+  ///
+  ///
+  Future setMaterialInstanceAt(
+      ThermionEntity entity, int primitiveIndex, MaterialInstance materialInstance);
 
   ///
   ///