diff --git a/_includes/responsive-image.html b/features/fixtures/_includes/responsive-image.html
similarity index 60%
rename from _includes/responsive-image.html
rename to features/fixtures/_includes/responsive-image.html
index 7111d43..fa6032c 100644
--- a/_includes/responsive-image.html
+++ b/features/fixtures/_includes/responsive-image.html
@@ -1,5 +1,5 @@
-<img alt="{{ alt }}" src="/{{ path }}" {% if resized %}srcset="
+<img alt="{{ alt }}" src="/{{ path }}"{% if resized %} srcset="
     {% for i in resized %}
         /{{ i.path }} {{ i.width }}w{% if forloop.last == false %},{% endif %}
     {% endfor %}
-" {% endif %}>
+"{% endif %}>
diff --git a/features/fixtures/assets/test.png b/features/fixtures/assets/test.png
new file mode 100644
index 0000000..e53ebca
Binary files /dev/null and b/features/fixtures/assets/test.png differ
diff --git a/features/responsive-image.feature b/features/responsive-image.feature
index 9693380..d636b74 100644
--- a/features/responsive-image.feature
+++ b/features/responsive-image.feature
@@ -10,7 +10,38 @@ Feature: Jekyll responsive-image tag
       """
     And I have a file "index.html" with:
       """
-        {% responsive_image path: assets/test.jpg %}
+      {% responsive_image path: assets/test.png alt: Foobar %}
       """
     When I run Jekyll
-    Then I should see "<img src=\"/assets/test.jpg\" alt=\"\">" in "_site/index.html"
+    Then I should see "<img alt=\"Foobar\" src=\"/assets/test.png\">" in "_site/index.html"
+
+  Scenario: UTF-8 alt attribute
+    Given I have a responsive_image configuration with:
+      """
+        template: _includes/responsive-image.html
+      """
+    And I have a file "index.html" with:
+      """
+      {% responsive_image path: assets/test.png alt: "かっこいい！ ジェケルが好きです！" %}
+      """
+    When I run Jekyll
+    Then I should see "<img alt=\"かっこいい！ ジェケルが好きです！\" src=\"/assets/test.png\">" in "_site/index.html"
+
+  Scenario: Image with multiple sizes
+    Given I have a responsive_image configuration with:
+      """
+        template: _includes/responsive-image.html
+        sizes:
+          - width: 100
+          - width: 200
+      """
+    And I have a file "index.html" with:
+      """
+      {% responsive_image path: assets/test.png %}
+      """
+    When I run Jekyll
+    Then I should see "<img alt=\"\" src=\"/assets/test.png\"" in "_site/index.html"
+    And I should see "/assets/resized/test-100x50.png 100w" in "_site/index.html"
+    And I should see "/assets/resized/test-200x100.png 200w" in "_site/index.html"
+    And the file "assets/resized/test-100x50.png" should exist
+    And the file "assets/resized/test-200x100.png" should exist
diff --git a/features/step_definitions/jekyll_steps.rb b/features/step_definitions/jekyll_steps.rb
index 7bbdaeb..48bfdba 100644
--- a/features/step_definitions/jekyll_steps.rb
+++ b/features/step_definitions/jekyll_steps.rb
@@ -6,14 +6,18 @@ Given /^I have a responsive_image configuration with:$/ do |config|
   write_file('_config.yml', "responsive_image:\n#{config}")
 end
 
-Given /^I have a file "([^\"]+)" with:$/ do |path, contents|
-  write_file(path, contents)
+Given /^I have a file "(.+)" with:$/ do |path, contents|
+  write_file(path, "---\n---\n#{contents}")
 end
 
-Then /^I should see "(.*)" in "(.*)"$/ do |text, file|
+Then /^I should see "(.+)" in "(.*)"$/ do |text, file|
   assert_match(Regexp.new(text), File.open(file).readlines.join)
 end
 
+Then /^the file "(.+)" should exist$/ do |path|
+  assert File.exists?(path)
+end
+
 def write_file(path, contents)
   File.open(path, 'w') do |f|
     f.write(contents)
diff --git a/features/support/hooks.rb b/features/support/hooks.rb
index c2911e8..ad0bb57 100644
--- a/features/support/hooks.rb
+++ b/features/support/hooks.rb
@@ -1,9 +1,13 @@
 Before do
   FileUtils.rm_rf(TEST_DIR) if File.exist?(TEST_DIR)
   FileUtils.mkdir_p(TEST_DIR)
+
+  fixtures = File.expand_path('../../fixtures', __FILE__)
+  FileUtils.cp_r(Dir.glob("#{fixtures}/*"), TEST_DIR)
+
   Dir.chdir(TEST_DIR)
 end
 
-After do
+at_exit do
   FileUtils.rm_rf(TEST_DIR) if File.exist?(TEST_DIR)
 end
diff --git a/lib/jekyll/responsive_image.rb b/lib/jekyll/responsive_image.rb
index 18c7a58..58e9185 100644
--- a/lib/jekyll/responsive_image.rb
+++ b/lib/jekyll/responsive_image.rb
@@ -19,13 +19,17 @@ module Jekyll
       end
 
       def resize_image(path, config)
+        sizes = config['sizes']
+
+        return if sizes.empty?
+
         output_dir = config['output_dir']
         ensure_output_dir_exists!(output_dir)
 
         resized = []
         img = Magick::Image::read(path).first
 
-        config['sizes'].each do |size|
+        sizes.each do |size|
           width = size['width']
           ratio = width.to_f / img.columns.to_f
           height = (img.rows.to_f * ratio).round