diff --git a/src/gallium/drivers/d3d12/d3d12_video_dec_vp9.cpp b/src/gallium/drivers/d3d12/d3d12_video_dec_vp9.cpp
index 7381ad4de5e..da1f2a3b998 100644
--- a/src/gallium/drivers/d3d12/d3d12_video_dec_vp9.cpp
+++ b/src/gallium/drivers/d3d12/d3d12_video_dec_vp9.cpp
@@ -217,7 +217,7 @@ d3d12_video_decoder_prepare_dxva_slices_control_vp9(struct d3d12_video_decoder *
    debug_printf("[d3d12_video_decoder_vp9] Upper layer reported %d slices for this frame, parsing them below...\n",
                   picture_vp9->slice_parameter.slice_count);
 
-   uint64_t TotalSlicesDXVAArrayByteSize = picture_vp9->slice_parameter.slice_count * sizeof(DXVA_Slice_VPx_Short);
+   size_t TotalSlicesDXVAArrayByteSize = picture_vp9->slice_parameter.slice_count * sizeof(DXVA_Slice_VPx_Short);
    vecOutSliceControlBuffers.resize(TotalSlicesDXVAArrayByteSize);
 
    uint8_t* pData = vecOutSliceControlBuffers.data();