diff --git a/widget/nsBaseWidget.cpp b/widget/nsBaseWidget.cpp
index 252f4aa06271..8f2b8b7de61a 100644
--- a/widget/nsBaseWidget.cpp
+++ b/widget/nsBaseWidget.cpp
@@ -1365,7 +1365,7 @@ nsBaseWidget::CreateBackBufferDrawTarget(mozilla::gfx::DrawTarget* aScreenTarget
                                          const LayoutDeviceIntRect& aRect)
 {
   MOZ_ASSERT(aScreenTarget);
-  gfx::SurfaceFormat format = aScreenTarget->GetFormat() == gfx::SurfaceFormat::B8G8R8X8 ? gfx::SurfaceFormat::B8G8R8X8 : gfx::SurfaceFormat::B8G8R8A8;
+  gfx::SurfaceFormat format = gfx::SurfaceFormat::B8G8R8A8;
   return aScreenTarget->CreateSimilarDrawTarget(aRect.ToUnknownRect().Size(), format);
 }