diff --git a/.gitignore b/.gitignore
index b61a9b05..b7afc813 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@
 
 Gemfile.lock
 Makefile
+.DS_Store
 *.o
 *.bundle
 /tmp/
diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
index f706c693..894c778d 100644
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -3,6 +3,7 @@
 ## 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)
+* Don't do anything when "optimized" version is larger and `:skip_bigger => true` [@R167](https://github.com/R167)
 
 ## v0.21.0 (2015-05-30)
 
diff --git a/README.markdown b/README.markdown
index 530ba887..c9d31c72 100644
--- a/README.markdown
+++ b/README.markdown
@@ -56,7 +56,7 @@ gem 'image_optim_pack'
 With version:
 
 ```ruby
-gem 'image_optim', '~> 0.11'
+gem 'image_optim', '~> 0.21'
 ```
 
 If you want to check latest changes:
@@ -271,6 +271,7 @@ optipng:
 * `:pack` — Require image\_optim\_pack or disable it, by default image\_optim\_pack will be used if available, will turn on `:skip-missing-workers` unless explicitly disabled *(defaults to `nil`)*
 * `:skip_missing_workers` — Skip workers with missing or problematic binaries *(defaults to `false`)*
 * `:allow_lossy` — Allow lossy workers and optimizations *(defaults to `false`)*
+* `:skip_bigger` — Perform sanity check (esp. on jpg) and only return if new image is smaller *(defaults to `false`)*
 
 Worker can be disabled by passing `false` instead of options hash or by setting option `:disable` to `true`.
 
diff --git a/lib/image_optim.rb b/lib/image_optim.rb
index 05b634f2..115ea280 100644
--- a/lib/image_optim.rb
+++ b/lib/image_optim.rb
@@ -37,6 +37,9 @@ class ImageOptim
   # Allow lossy workers and optimizations
   attr_reader :allow_lossy
 
+  # Skip images where optimization makes them bigger
+  attr_reader :skip_bigger
+
   # Initialize workers, specify options using worker underscored name:
   #
   # pass false to disable worker
@@ -67,6 +70,7 @@ def initialize(options = {})
       pack
       skip_missing_workers
       allow_lossy
+      skip_bigger
     ].each do |name|
       instance_variable_set(:"@#{name}", config.send(name))
       $stderr << "#{name}: #{send(name)}\n" if verbose
@@ -101,6 +105,7 @@ def optimize_image(original)
       end
     end
     return unless result
+    return if skip_bigger && result.size > original.size
     ImagePath::Optimized.new(result, original)
   end
 
diff --git a/lib/image_optim/config.rb b/lib/image_optim/config.rb
index 37b767c5..2c076ca9 100644
--- a/lib/image_optim/config.rb
+++ b/lib/image_optim/config.rb
@@ -133,6 +133,11 @@ def pack
       false
     end
 
+    # Whether or not to perfom size sanity check
+    def skip_bigger
+      !!get!(:skip_bigger)
+    end
+
     # Skip missing workers, converted to boolean
     def skip_missing_workers
       if key?(:skip_missing_workers)
diff --git a/lib/image_optim/runner/option_parser.rb b/lib/image_optim/runner/option_parser.rb
index 7637eab8..882730b7 100644
--- a/lib/image_optim/runner/option_parser.rb
+++ b/lib/image_optim/runner/option_parser.rb
@@ -143,6 +143,11 @@ def wrap_regex(width)
     options[:pack] = pack
   end
 
+  op.on('--[no-]skip-bigger', 'Skip files that end up becoming larger. '\
+      '(defaults to false)') do |skip_bigger|
+    options[:skip_bigger] = skip_bigger
+  end
+
   op.separator nil
   op.separator '  Disabling workers:'
 
diff --git a/spec/image_optim/config_spec.rb b/spec/image_optim/config_spec.rb
index bfb7d8a3..27fcacf0 100644
--- a/spec/image_optim/config_spec.rb
+++ b/spec/image_optim/config_spec.rb
@@ -45,6 +45,27 @@
     end
   end
 
+  describe :skip_bigger do
+    before do
+      allow(IOConfig).to receive(:read_options).and_return({})
+    end
+
+    it 'is true by default' do
+      config = IOConfig.new({})
+      expect(config.skip_bigger).to be false
+    end
+
+    it 'is false when false' do
+      config = IOConfig.new(:skip_bigger => true)
+      expect(config.skip_bigger).to be true
+    end
+
+    it 'is false when false' do
+      config = IOConfig.new(:skip_bigger => false)
+      expect(config.skip_bigger).to be false
+    end
+  end
+
   describe :threads do
     before do
       allow(IOConfig).to receive(:read_options).and_return({})
diff --git a/spec/image_optim_spec.rb b/spec/image_optim_spec.rb
index d3dadf38..59f3f4b7 100644
--- a/spec/image_optim_spec.rb
+++ b/spec/image_optim_spec.rb
@@ -89,6 +89,33 @@ def temp_copy(image)
           end
         end
       end
+
+      describe 'skipping larger' do
+        let(:original){ double(:size => 12_345) }
+        let(:optimized){ double(:original_size => 12_345, :size => 100_000) }
+
+        it 'skips larger files' do
+          image_optim = ImageOptim.new(:skip_bigger => true)
+
+          allow(ImageOptim::ImagePath).to receive(:convert).and_return original
+          allow(image_optim).to receive(:workers_for_image).with(original).
+            and_return([])
+          allow(ImageOptim::Handler).to receive(:for).and_return optimized
+
+          expect(image_optim.optimize_image(original)).to be nil
+        end
+
+        it 'does not skips larger files when opt is off' do
+          image_optim = ImageOptim.new(:skip_bigger => false)
+
+          allow(ImageOptim::ImagePath).to receive(:convert).and_return original
+          allow(image_optim).to receive(:workers_for_image).with(original).
+            and_return([])
+          allow(ImageOptim::Handler).to receive(:for).and_return optimized
+
+          expect(image_optim.optimize_image(original)).to_not be nil
+        end
+      end
     end
 
     it 'ignores text file' do