diff --git a/README.markdown b/README.markdown
index 6b9f6546..e29158de 100644
--- a/README.markdown
+++ b/README.markdown
@@ -352,6 +352,9 @@ Worker has no options
 * `:max_colors` — Maximum number of colors to use *(defaults to `256`)*
 * `:quality` — min..max - don't save below min, use less colors below max (both in range `0..100`; in yaml - `!ruby/range 0..100`), ignored in default/lossless mode *(defaults to `100..100`, `0..100` in lossy mode)*
 * `:speed` — speed/quality trade-off: `1` - slow, `3` - default, `11` - fast & rough *(defaults to `3`)*
+* `:floyd` - Set dithering level using fractional number between 0 (none) and 1 (full, the default)
+* `:nofs` - Disable Floyd-Steinberg dithering *(defaults to `false`)*
+* `:strip` - Remove optional chunks (metadata) from PNG files *(defaults to `false`)*
 
 ### svgo:
 * `:disable_plugins` — List of plugins to disable *(defaults to `[]`)*
diff --git a/lib/image_optim/worker/pngquant.rb b/lib/image_optim/worker/pngquant.rb
index f69e2870..bf29e4be 100644
--- a/lib/image_optim/worker/pngquant.rb
+++ b/lib/image_optim/worker/pngquant.rb
@@ -46,6 +46,22 @@ class Pngquant < Worker
         OptionHelpers.limit_with_range(v.to_i, 1..11)
       end
 
+      # NOFS_OPTION =
+      option(:nofs, false, 'Disable Floyd-Steinberg dithering') do |v|
+        v ? '--nofs' : ''
+      end
+
+      # FLOYD_OPTION =
+      option(:floyd, false, 'Set dithering level using fractional number '\
+                            'between 0 (none) and 1 (full, the default)') do |v|
+        v ? "--floyd=#{v}" : ''
+      end
+
+      # STRIP_OPTION =
+      option(:strip, false, 'Remove optional chunks (metadata) from PNG files') do |v|
+        v ? '--strip' : ''
+      end
+
       def run_order
         -2
       end
@@ -57,10 +73,14 @@ def optimize(src, dst, options = {})
           --output=#{dst}
           --skip-if-larger
           --force
+          #{nofs}
+          #{floyd}
+          #{strip}
           #{max_colors}
           --
           #{src}
-        ]
+        ].reject(&:empty?)
+
         execute(:pngquant, args, options) && optimized?(src, dst)
       end
     end