--- a/gfx/layers/client/CanvasClient.h
+++ b/gfx/layers/client/CanvasClient.h
@@ -11,18 +11,16 @@
 #include "mozilla/Attributes.h"         // for override
 #include "mozilla/RefPtr.h"             // for RefPtr, already_AddRefed
 #include "mozilla/layers/CompositableClient.h"  // for CompositableClient
 #include "mozilla/layers/CompositorTypes.h"  // for TextureInfo, etc
 #include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor
 #include "mozilla/layers/TextureClient.h"  // for TextureClient, etc
 #include "mozilla/layers/PersistentBufferProvider.h"
 
-// Fix X11 header brain damage that conflicts with MaybeOneOf::None
-#undef None
 #include "mozilla/MaybeOneOf.h"
 
 #include "mozilla/mozalloc.h"           // for operator delete
 
 #include "mozilla/gfx/Point.h"          // for IntSize
 #include "mozilla/gfx/Types.h"          // for SurfaceFormat
 
 namespace mozilla {