diff --git a/lib/rendercore_optix7/rendercore.cpp b/lib/rendercore_optix7/rendercore.cpp
index 6e2bbc83..abcda1f7 100644
--- a/lib/rendercore_optix7/rendercore.cpp
+++ b/lib/rendercore_optix7/rendercore.cpp
@@ -515,7 +515,7 @@ void RenderCore::SetMaterials( CoreMaterial* mat, const int materialCount )
 	if (materialBuffer == 0 || materialCount > materialBuffer->GetSize())
 	{
 		delete hostMaterialBuffer;
-	hostMaterialBuffer = new CUDAMaterial[materialCount];
+		hostMaterialBuffer = new CUDAMaterial[materialCount + 512];
 	}
 	for (int i = 0; i < materialCount; i++)
 	{
@@ -556,9 +556,11 @@ void RenderCore::SetMaterials( CoreMaterial* mat, const int materialCount )
 		// just set the new material data
 		materialBuffer->SetHostData( hostMaterialBuffer );
 	}
-	else /* if (materialCount > materialBuffer->GetSize()) */
+	else if (materialCount > materialBuffer->GetSize())
 	{
 		// TODO: realloc, remove +512 during allocation
+		delete materialBuffer;
+		materialBuffer = new CoreBuffer<CUDAMaterial>( materialCount + 512, ON_HOST | ON_DEVICE | STAGED, hostMaterialBuffer );
 	}
 	materialBuffer->StageCopyToDevice();
 	stageMaterialList( materialBuffer->DevPtr() );