diff --git a/src/core/Object3D.d.ts b/src/core/Object3D.d.ts
index 24035c68ce51df8fef10aa28fb7a090ef12ccc7e..7c643cc2097a05122da831c47f5ba7dbab6be613 100644
--- a/src/core/Object3D.d.ts
+++ b/src/core/Object3D.d.ts
@@ -306,7 +306,7 @@ export class Object3D extends EventDispatcher {
   /**
    * Updates global transform of the object and its children.
    */
-  updateMatrixWorld(force: boolean): void;
+  updateMatrixWorld(force?: boolean): void;
 
   updateWorldMatrix(updateParents: boolean, updateChildren: boolean): void;