--- a/gfx/2d/BaseRect.h
+++ b/gfx/2d/BaseRect.h
@@ -4,17 +4,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef MOZILLA_GFX_BASERECT_H_
 #define MOZILLA_GFX_BASERECT_H_
 
 #include <cmath>
 #include <mozilla/Assertions.h>
 #include <algorithm>
-#include "nsMathUtils.h"
 
 namespace mozilla {
 namespace gfx {
 
 /**
  * Rectangles have two interpretations: a set of (zero-size) points,
  * and a rectangular area of the plane. Most rectangle operations behave
  * the same no matter what interpretation is being used, but some operations
@@ -55,20 +54,20 @@ struct BaseRect {
   // Emptiness. An empty rect is one that has no area, i.e. its height or width
   // is <= 0
   bool IsEmpty() const { return height <= 0 || width <= 0; }
   void SetEmpty() { width = height = 0; }
 
   // "Finite" means not inf and not NaN
   bool IsFinite() const
   {
-    return (NS_finite(x) &&
-            NS_finite(y) &&
-            NS_finite(width) &&
-            NS_finite(height));
+    return (std::isfinite(x) &&
+            std::isfinite(y) &&
+            std::isfinite(width) &&
+            std::isfinite(height));
   }
 
   // Returns true if this rectangle contains the interior of aRect. Always
   // returns true if aRect is empty, and always returns false is aRect is
   // nonempty but this rect is empty.
   bool Contains(const Sub& aRect) const
   {
     return aRect.IsEmpty() ||