diff --git a/gfx/ipc/GfxMessageUtils.h b/gfx/ipc/GfxMessageUtils.h
index 3c7bcb50685c..f09c9d583bf6 100644
--- a/gfx/ipc/GfxMessageUtils.h
+++ b/gfx/ipc/GfxMessageUtils.h
@@ -7,25 +7,25 @@
 #ifndef __GFXMESSAGEUTILS_H__
 #define __GFXMESSAGEUTILS_H__
 
+#include "FilterSupport.h"
+#include "FrameMetrics.h"
+#include "ImageTypes.h"
+#include "RegionBuilder.h"
 #include "base/process_util.h"
 #include "chrome/common/ipc_message_utils.h"
-#include "ipc/IPCMessageUtils.h"
-
-#include <stdint.h>
-
-#include "mozilla/gfx/Matrix.h"
 #include "gfxPoint.h"
 #include "gfxRect.h"
+#include "gfxTypes.h"
+#include "ipc/IPCMessageUtils.h"
+#include "mozilla/gfx/Matrix.h"
+#include "mozilla/layers/AsyncDragMetrics.h"
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/layers/GeckoContentController.h"
+#include "mozilla/layers/LayersTypes.h"
 #include "nsRect.h"
 #include "nsRegion.h"
-#include "gfxTypes.h"
-#include "mozilla/layers/AsyncDragMetrics.h"
-#include "mozilla/layers/LayersTypes.h"
-#include "mozilla/layers/CompositorTypes.h"
-#include "ImageTypes.h"
-#include "FrameMetrics.h"
-#include "FilterSupport.h"
-#include "mozilla/layers/GeckoContentController.h"
+
+#include <stdint.h>
 
 #ifdef _MSC_VER
 #pragma warning( disable : 4800 )
@@ -367,6 +367,7 @@ struct RegionParamTraits
 
   static void Write(Message* msg, const paramType& param)
   {
+
     for (auto iter = param.RectIter(); !iter.Done(); iter.Next()) {
       const Rect& r = iter.Get();
       MOZ_RELEASE_ASSERT(!r.IsEmpty());
@@ -379,12 +380,16 @@ struct RegionParamTraits
 
   static bool Read(const Message* msg, void** iter, paramType* result)
   {
+    RegionBuilder<Region> builder;
     Rect rect;
     while (ReadParam(msg, iter, &rect)) {
-      if (rect.IsEmpty())
+      if (rect.IsEmpty()) {
+        *result = builder.ToRegion();
         return true;
-      result->Or(*result, rect);
+      }
+      builder.Or(rect);
     }
+
     return false;
   }
 };
diff --git a/gfx/src/nsRegion.h b/gfx/src/nsRegion.h
index f8857c8a29db..1293b8837a0d 100644
--- a/gfx/src/nsRegion.h
+++ b/gfx/src/nsRegion.h
@@ -831,7 +831,7 @@ public:
   // Forward constructors.
   IntRegionTyped() {}
   MOZ_IMPLICIT IntRegionTyped(const IntRectTyped<units>& aRect) : Super(aRect) {}
-  IntRegionTyped(const IntRegionTyped& aRegion) : Super(aRegion) {}
+  explicit IntRegionTyped(const IntRegionTyped& aRegion) : Super(aRegion) {}
   IntRegionTyped(const nsTArray<pixman_box32_t>& aRects) : Super(aRects) {}
   IntRegionTyped(IntRegionTyped&& aRegion) : Super(mozilla::Move(aRegion)) {}