diff --git a/lib/image_optim/worker/pngquant.rb b/lib/image_optim/worker/pngquant.rb
index 110ebff9..2a23a31e 100644
--- a/lib/image_optim/worker/pngquant.rb
+++ b/lib/image_optim/worker/pngquant.rb
@@ -45,6 +45,7 @@ def optimize(src, dst)
           --quality=#{quality.begin}-#{quality.end}
           --speed=#{speed}
           --output=#{dst}
+          --skip-if-larger
           --force
           --
           #{src}