diff --git a/common/obj_loader.h b/common/obj_loader.h
index e5532de..6ab0870 100644
--- a/common/obj_loader.h
+++ b/common/obj_loader.h
@@ -26,6 +26,7 @@ struct MaterialObj
   int textureID = -1;
 };
 // OBJ representation of a vertex
+// NOTE: BLAS builder depends on pos being the first member
 struct VertexObj
 {
   nvmath::vec3f pos;