diff --git a/src/d3d9/d3d9_device.h b/src/d3d9/d3d9_device.h
index 0a318a2a0..719721134 100644
--- a/src/d3d9/d3d9_device.h
+++ b/src/d3d9/d3d9_device.h
@@ -1090,7 +1090,7 @@ namespace dxvk {
     }
 
     inline uint32_t GetUPBufferSize(uint32_t vertexCount, uint32_t stride) {
-      return (vertexCount - 1) * stride + m_state.vertexDecl->GetSize();
+      return (vertexCount - 1) * stride + std::max(m_state.vertexDecl->GetSize(), stride);
     }
 
     inline void FillUPVertexBuffer(void* buffer, const void* userData, uint32_t dataSize, uint32_t bufferSize) {