diff --git a/lib/jekyll/tags/gist.rb b/lib/jekyll/tags/gist.rb
index d3eb0b37cfd..0d981af11a3 100644
--- a/lib/jekyll/tags/gist.rb
+++ b/lib/jekyll/tags/gist.rb
@@ -2,16 +2,27 @@
 #
 # Example:
 #    {% gist 1234567 %}
+#    {% gist 1234567 file.rb %}
 
 module Jekyll
   class GistTag < Liquid::Tag
-    def initialize(tag_name, gist, tokens)
-      super
-      @gist = gist.strip
+    def render(context)
+      if tag_contents = @markup.strip.match(/\A(\d+) ?(\S*)\Z/)
+        gist_id, filename = tag_contents[1].strip, tag_contents[2].strip
+        gist_script_tag(gist_id, filename)
+      else
+        "Error parsing gist id"
+      end
     end
 
-    def render(context)
-      "<script src=\"https://gist.github.com/#{@gist}.js\"> </script>"
+    private
+
+    def gist_script_tag(gist_id, filename=nil)
+      if filename.empty?
+        "<script src=\"https://gist.github.com/#{gist_id}.js\"> </script>"
+      else
+        "<script src=\"https://gist.github.com/#{gist_id}.js?file=#{filename}\"> </script>"
+      end
     end
   end
 end
diff --git a/test/test_tags.rb b/test/test_tags.rb
index caefb9ac823..f7916fc5111 100644
--- a/test/test_tags.rb
+++ b/test/test_tags.rb
@@ -170,7 +170,7 @@ def fill_post(code, override = {})
         assert_match %r{<em>FINISH HIM</em>}, @result
       end
     end
-    
+
     context "using Redcarpet" do
       setup do
         create_post(@content, 'markdown' => 'redcarpet')
@@ -203,22 +203,78 @@ def fill_post(code, override = {})
       assert_match %r{/2008/11/21/complex/}, @result
     end
   end
-  
-  context "simple gist inclusion" do
-    setup do
-      @gist = 358471
-      content = <<CONTENT
+
+  context "gist tag" do
+    context "simple" do
+      setup do
+        @gist = 358471
+        content = <<CONTENT
 ---
 title: My Cool Gist
 ---
 
 {% gist #{@gist} %}
 CONTENT
-      create_post(content, {'permalink' => 'pretty', 'source' => source_dir, 'destination' => dest_dir, 'read_posts' => true})
+        create_post(content, {'permalink' => 'pretty', 'source' => source_dir, 'destination' => dest_dir, 'read_posts' => true})
+      end
+
+      should "write script tag" do
+        assert_match "<script src='https://gist.github.com/#{@gist}.js'>\s</script>", @result
+      end
     end
-    
-    should "write script tag" do
-      assert_match %r{<script src='https://gist.github.com/#{@gist}.js'>\s</script>}, @result
+
+    context "with specific file" do
+      setup do
+        @gist = 358471
+        @filename = 'somefile.rb'
+        content = <<CONTENT
+---
+title: My Cool Gist
+---
+
+{% gist #{@gist} #{@filename} %}
+CONTENT
+        create_post(content, {'permalink' => 'pretty', 'source' => source_dir, 'destination' => dest_dir, 'read_posts' => true})
+      end
+
+      should "write script tag with specific file in gist" do
+        assert_match "<script src='https://gist.github.com/#{@gist}.js?file=#{@filename}'>\s</script>", @result
+      end
+    end
+
+    context "with blank gist id" do
+      setup do
+        content = <<CONTENT
+---
+title: My Cool Gist
+---
+
+{% gist %}
+CONTENT
+        create_post(content, {'permalink' => 'pretty', 'source' => source_dir, 'destination' => dest_dir, 'read_posts' => true})
+      end
+
+      should "output error message" do
+        assert_match "Error parsing gist id", @result
+      end
+    end
+
+    context "with invalid gist id" do
+      setup do
+        invalid_gist = 'invalid'
+        content = <<CONTENT
+---
+title: My Cool Gist
+---
+
+{% gist #{invalid_gist} %}
+CONTENT
+        create_post(content, {'permalink' => 'pretty', 'source' => source_dir, 'destination' => dest_dir, 'read_posts' => true})
+      end
+
+      should "output error message" do
+        assert_match "Error parsing gist id", @result
+      end
     end
   end
 end