--- a/dom/animation/ComputedTiming.h
+++ b/dom/animation/ComputedTiming.h
@@ -6,20 +6,16 @@
 
 #ifndef mozilla_ComputedTiming_h
 #define mozilla_ComputedTiming_h
 
 #include "mozilla/dom/Nullable.h"
 #include "mozilla/StickyTimeDuration.h"
 #include "mozilla/ComputedTimingFunction.h"
 
-// X11 has a #define for None
-#ifdef None
-#undef None
-#endif
 #include "mozilla/dom/AnimationEffectReadOnlyBinding.h" // FillMode
 
 namespace mozilla {
 
 /**
  * Stores the results of calculating the timing properties of an animation
  * at a given sample time.
  */

--- a/dom/animation/KeyframeEffectParams.h
+++ b/dom/animation/KeyframeEffectParams.h
@@ -2,20 +2,16 @@
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef mozilla_KeyframeEffectParams_h
 #define mozilla_KeyframeEffectParams_h
 
-// X11 has a #define for None
-#ifdef None
-#undef None
-#endif
 #include "mozilla/dom/KeyframeEffectBinding.h" // IterationCompositeOperation
 
 namespace mozilla {
 
 struct KeyframeEffectParams
 {
   dom::IterationCompositeOperation mIterationComposite =
     dom::IterationCompositeOperation::Replace;

--- a/dom/animation/TimingParams.h
+++ b/dom/animation/TimingParams.h
@@ -10,20 +10,16 @@
 #include "nsStringFwd.h"
 #include "mozilla/dom/Nullable.h"
 #include "mozilla/dom/UnionTypes.h" // For OwningUnrestrictedDoubleOrString
 #include "mozilla/ComputedTimingFunction.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/StickyTimeDuration.h"
 #include "mozilla/TimeStamp.h" // for TimeDuration
 
-// X11 has a #define for None
-#ifdef None
-#undef None
-#endif
 #include "mozilla/dom/AnimationEffectReadOnlyBinding.h" // for FillMode
                                                         // and PlaybackDirection
 
 class nsIDocument;
 
 namespace mozilla {
 
 namespace dom {