diff --git a/src/c/lesson9.c b/src/c/lesson9.c
index 4030554..0426ce0 100644
--- a/src/c/lesson9.c
+++ b/src/c/lesson9.c
@@ -178,7 +178,7 @@ static bool Lesson9_Init(NeHeContext* ctx)
 	instanceXferBuffer = SDL_CreateGPUTransferBuffer(ctx->device, &(const SDL_GPUTransferBufferCreateInfo)
 	{
 		.usage = SDL_GPU_TRANSFERBUFFERUSAGE_UPLOAD,
-		.size = sizeof(Instance) * numStars
+		.size = sizeof(Instance) * 2 * numStars
 	});
 	if (!instanceXferBuffer)
 	{