--- a/gfx/layers/wr/WebRenderCommandBuilder.cpp
+++ b/gfx/layers/wr/WebRenderCommandBuilder.cpp
@@ -530,17 +530,20 @@ struct DIGroup
         InvalidateRect(data->mRect);
         iter.Remove();
         delete data;
       } else {
         data->mUsed = false;
       }
     }
 
+    // Round the bounds in a way that matches the existing fallback code
     LayoutDeviceRect bounds = LayoutDeviceRect::FromAppUnits(mGroupBounds, aGrouper->mAppUnitsPerDevPixel);
+    bounds = LayoutDeviceRect(RoundedToInt(bounds));
+
     IntSize size = mGroupBounds.Size().ScaleToNearestPixels(mScale.width, mScale.height, aGrouper->mAppUnitsPerDevPixel);
 
     if (mInvalidRect.IsEmpty()) {
       GP("Not repainting group because it's empty\n");
       GP("End EndGroup\n");
       if (mKey) {
         PushImage(aBuilder, bounds);
       }