diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 3025c09a7b3..25b81b0b121 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -1180,8 +1180,16 @@ AddItemsToRegion(nsDisplayListBuilder* aBuilder, nsDisplayList* aList,
         // If the clipping frame is moving, then it isn't clipping any
         // non-moving content (see ApplyAbsPosClipping), so we don't need
         // to do anything special, but we should not restrict aClipRect.
-        if (!aBuilder->IsMovingFrame(clipItem->GetClippingFrame())) {
-          clip.IntersectRect(clip, clipItem->GetClipRect());
+        nsIFrame* clipFrame = clipItem->GetClippingFrame();
+        if (!aBuilder->IsMovingFrame(clipFrame)) {
+          nscoord appUnitsPerDevPixel = clipFrame->PresContext()->AppUnitsPerDevPixel();
+          // We know the nsDisplayClip will snap because we're in a context
+          // where pixels can be blitted and we don't traverse down through
+          // an nsDisplayTransform.
+          nsRect snappedClip =
+            clipItem->GetClipRect().ToNearestPixels(appUnitsPerDevPixel).
+            ToAppUnits(appUnitsPerDevPixel);
+          clip.IntersectRect(clip, snappedClip);
 
           // Invalidate the translation of the source area that was clipped out
           nsRegion clippedOutSource;
diff --git a/layout/base/tests/scrolling_helper.html b/layout/base/tests/scrolling_helper.html
index 33b5fb548f8..3b974ee2b44 100644
--- a/layout/base/tests/scrolling_helper.html
+++ b/layout/base/tests/scrolling_helper.html
@@ -197,8 +197,8 @@ function testSimpleScrollWithSubpixelOffset2(blitRegion, paintRegion) {
   ok(paintRegion.containsRegion(new Region([[0,181,200,200]])),
      "Should repaint area that was scrolled into view: " + paintRegion.toString());
   // Check that we're not repainting anything in the area that's blitted
-  todo(!paintRegion.intersectsRect([0,0,200,180]),
-       "Should not repaint area that was blitted: " + paintRegion.toString());
+  ok(!paintRegion.intersectsRect([0,0,200,180]),
+     "Should not repaint area that was blitted: " + paintRegion.toString());
 }
 
 function testSimpleScrollWithSubpixelOffset3(blitRegion, paintRegion) {
@@ -221,8 +221,8 @@ function testSimpleScrollWithSubpixelOffset4(blitRegion, paintRegion) {
   ok(paintRegion.containsRegion(new Region([[181,0,200,200]])),
      "Should repaint area that was scrolled into view: " + paintRegion.toString());
   // Check that we're not repainting anything in the area that's blitted
-  todo(!paintRegion.intersectsRect([0,0,180,200]),
-       "Should not repaint area that was blitted: " + paintRegion.toString());
+  ok(!paintRegion.intersectsRect([0,0,180,200]),
+     "Should not repaint area that was blitted: " + paintRegion.toString());
 }
 
 function testMovingClipArea(blitRegion, paintRegion) {
diff --git a/view/src/nsViewManager.cpp b/view/src/nsViewManager.cpp
index 294e119a467..e4b87e90450 100644
--- a/view/src/nsViewManager.cpp
+++ b/view/src/nsViewManager.cpp
@@ -1480,6 +1480,13 @@ void nsViewManager::GetRegionsForBlit(nsView* aView, nsPoint aDelta,
   nsView* displayRoot = GetDisplayRootFor(aView);
   nsPoint displayOffset = aView->GetParent()->GetOffsetTo(displayRoot);
   nsRect parentBounds = aView->GetParent()->GetDimensions() + displayOffset;
+
+  // The area clipped by the scrolling view is snapped to device pixels
+  // (in nsThebesRenderingContext::SetClipRect), so snap the bound here
+  // that we use to compute the blit and repaint regions
+  PRInt32 p2a = mContext->AppUnitsPerDevPixel();
+  parentBounds = parentBounds.ToNearestPixels(p2a).ToAppUnits(p2a);
+
   if (IsPainting() || !mObserver) {
     // Be simple and safe
     aBlitRegion->SetEmpty();