--- a/gfx/2d/DrawTargetTiled.cpp
+++ b/gfx/2d/DrawTargetTiled.cpp
@@ -25,33 +25,32 @@ DrawTargetTiled::Init(const TileSet& aTi
 
   mTiles.reserve(aTiles.mTileCount);
   for (size_t i = 0; i < aTiles.mTileCount; ++i) {
     mTiles.push_back(TileInternal(aTiles.mTiles[i]));
     if (!aTiles.mTiles[i].mDrawTarget) {
       return false;
     }
     if (mTiles[0].mDrawTarget->GetFormat() != mTiles.back().mDrawTarget->GetFormat() ||
-        mTiles[0].mDrawTarget->GetBackendType() != mTiles.back().mDrawTarget->GetBackendType() ||
-        mTiles[0].mDrawTarget->GetPermitSubpixelAA() != mTiles.back().mDrawTarget->GetPermitSubpixelAA()) {
+        mTiles[0].mDrawTarget->GetBackendType() != mTiles.back().mDrawTarget->GetBackendType()) {
       return false;
     }
     uint32_t newXMost = max(mRect.XMost(),
                             mTiles[i].mTileOrigin.x + mTiles[i].mDrawTarget->GetSize().width);
     uint32_t newYMost = max(mRect.YMost(),
                             mTiles[i].mTileOrigin.y + mTiles[i].mDrawTarget->GetSize().height);
     mRect.x = min(mRect.x, mTiles[i].mTileOrigin.x);
     mRect.y = min(mRect.y, mTiles[i].mTileOrigin.y);
     mRect.width = newXMost - mRect.x;
     mRect.height = newYMost - mRect.y;
     mTiles[i].mDrawTarget->SetTransform(Matrix::Translation(mTiles[i].mTileOrigin.x,
                                                             mTiles[i].mTileOrigin.y));
   }
   mFormat = mTiles[0].mDrawTarget->GetFormat();
-  mPermitSubpixelAA = mTiles[0].mDrawTarget->GetPermitSubpixelAA();
+  SetPermitSubpixelAA(IsOpaque(mFormat));
   return true;
 }
 
 already_AddRefed<SourceSurface>
 DrawTargetTiled::Snapshot()
 {
   return MakeAndAddRef<SnapshotTiled>(mTiles, mRect);
 }