diff --git a/src/SceneGraph/RenderAssignBuffer.cpp b/src/SceneGraph/RenderAssignBuffer.cpp
index c33b2959..f3d46aa2 100644
--- a/src/SceneGraph/RenderAssignBuffer.cpp
+++ b/src/SceneGraph/RenderAssignBuffer.cpp
@@ -59,6 +59,7 @@ void RenderAssignBuffer::WriteNode(RenderNode *render_node,const uint count,cons
 
     Alloc(count,mi_set.GetCount());
 
+    if(ubo_mi)
     {
         uint8 *mip=(uint8 *)(ubo_mi->Map());