diff --git a/intern/cycles/hydra/render_buffer.cpp b/intern/cycles/hydra/render_buffer.cpp
index 4d8b21d..eb14808 100644
--- a/intern/cycles/hydra/render_buffer.cpp
+++ b/intern/cycles/hydra/render_buffer.cpp
@@ -191,7 +191,7 @@ void HdCyclesRenderBuffer::WritePixels(const float *srcPixels,
                                        int srcChannels,
                                        bool isId)
 {
-  uint8_t *dstPixels = _data.data();
+  uint8_t *dstPixels = Map();
 
   const size_t formatSize = HdDataSizeOfFormat(_format);
   dstPixels += srcOffset[1] * (formatSize * _width) + srcOffset[0] * formatSize;
@@ -283,6 +283,8 @@ void HdCyclesRenderBuffer::WritePixels(const float *srcPixels,
       TF_RUNTIME_ERROR("HdCyclesRenderBuffer::WritePixels called with unsupported format.");
       break;
   }
+
+  Unmap();
 }
 
 HDCYCLES_NAMESPACE_CLOSE_SCOPE