diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
index 84a07fda..f706c693 100644
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -2,6 +2,8 @@
 
 ## unreleased
 
+* Use quality `0..100` by default in lossy mode of pngquant worker [#77](https://github.com/toy/image_optim/issues/77) [@toy](https://github.com/toy)
+
 ## v0.21.0 (2015-05-30)
 
 * Use exifr 1.2.2 with fix for a bug [#85](https://github.com/toy/image_optim/issues/85) [@toy](https://github.com/toy)
diff --git a/lib/image_optim/worker/pngquant.rb b/lib/image_optim/worker/pngquant.rb
index 2eee01a0..202deaa0 100644
--- a/lib/image_optim/worker/pngquant.rb
+++ b/lib/image_optim/worker/pngquant.rb
@@ -7,19 +7,24 @@ class Worker
     # http://pngquant.org/
     class Pngquant < Worker
       QUALITY_OPTION =
-      option(:quality, 100..100, NonNegativeIntegerRange, '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') do |v, opt_def|
+      option(:quality, '100..100, 0..100 in lossy mode',
+             NonNegativeIntegerRange, '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') do |v, opt_def|
         if allow_lossy
-          min = OptionHelpers.limit_with_range(v.begin, 0..100)
-          min..OptionHelpers.limit_with_range(v.end, min..100)
+          if v == opt_def.default
+            0..100
+          else
+            min = OptionHelpers.limit_with_range(v.begin, 0..100)
+            min..OptionHelpers.limit_with_range(v.end, min..100)
+          end
         else
           if v != opt_def.default
             warn "#{self.class.bin_sym} #{opt_def.name} #{v} ignored " \
                 'in lossless mode'
           end
-          opt_def.default
+          100..100
         end
       end
 
diff --git a/spec/image_optim/worker/pngquant_spec.rb b/spec/image_optim/worker/pngquant_spec.rb
new file mode 100644
index 00000000..894f0c88
--- /dev/null
+++ b/spec/image_optim/worker/pngquant_spec.rb
@@ -0,0 +1,27 @@
+require 'spec_helper'
+require 'image_optim/worker/pngquant'
+
+describe ImageOptim::Worker::Pngquant do
+  describe 'quality option' do
+    describe 'default' do
+      subject{ described_class::QUALITY_OPTION.default }
+
+      it{ is_expected.to match(/100\.\.100.*0\.\.100/) }
+    end
+
+    describe 'value' do
+      let(:options){ {} }
+      subject{ described_class.new(ImageOptim.new, options).quality }
+
+      context 'by default' do
+        it{ is_expected.to eq(100..100) }
+      end
+
+      context 'when lossy allowed by default' do
+        let(:options){ {:allow_lossy => true} }
+
+        it{ is_expected.to eq(0..100) }
+      end
+    end
+  end
+end
diff --git a/spec/image_optim_spec.rb b/spec/image_optim_spec.rb
index 3eebd081..e8466d43 100644
--- a/spec/image_optim_spec.rb
+++ b/spec/image_optim_spec.rb
@@ -67,7 +67,7 @@ def temp_copy(image)
       base_options = {:skip_missing_workers => false}
       [
         ['lossless', base_options, 0],
-        ['lossy', base_options.merge(:allow_lossy => true), 0.01],
+        ['lossy', base_options.merge(:allow_lossy => true), 0.025],
       ].each do |type, options, max_difference|
         image_optim = ImageOptim.new(options)
         describe type do