diff --git a/.gitignore b/.gitignore
index f301dd4..54583c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ jhw-test
 _site/
 jhw.*.html
 coverage/
+tmp/
diff --git a/lib/jasmine/headless/file_checker.rb b/lib/jasmine/headless/file_checker.rb
index 749f054..fd7a3a7 100644
--- a/lib/jasmine/headless/file_checker.rb
+++ b/lib/jasmine/headless/file_checker.rb
@@ -1,10 +1,21 @@
 module Jasmine::Headless::FileChecker
   def bad_format?(file)
     return if file.nil?
-    ::Jasmine::Headless::EXCLUDED_FORMATS.any? {|format| file.include?(".#{format}") }
+
+    ::Jasmine::Headless::EXCLUDED_FORMATS.any? do |format|
+      file[%r{\.#{format}(\.|$)}]
+    end
   end
   
   def alert_bad_format(file)
     puts "[%s] %s: %s" % [ 'Skipping File'.color(:red), file.color(:yellow), "unsupported format".color(:white) ]
   end
-end
\ No newline at end of file
+
+  def alert_if_bad_format?(file)
+    if result = bad_format?(file)
+      alert_bad_format(file)
+    end
+
+    result
+  end
+end
diff --git a/lib/jasmine/headless/files_list.rb b/lib/jasmine/headless/files_list.rb
index 1c8a069..27f54ab 100644
--- a/lib/jasmine/headless/files_list.rb
+++ b/lib/jasmine/headless/files_list.rb
@@ -6,8 +6,9 @@ require 'sprockets'
 require 'sprockets/engines'
 
 module Jasmine::Headless
-  
   class FilesList
+    include FileChecker
+
     class << self
       def vendor_asset_paths
         return @vendor_asset_paths if @vendor_asset_paths
@@ -40,7 +41,7 @@ module Jasmine::Headless
 
         # ...and unregister ones we don't want/need
         Sprockets.instance_eval do
-         EXCLUDED_FORMATS.each do |extension|
+          EXCLUDED_FORMATS.each do |extension|
             register_engine ".#{extension}", Jasmine::Headless::NilTemplate
           end
 
@@ -54,6 +55,12 @@ module Jasmine::Headless
       def default_files
         %w{jasmine.js jasmine-html jasmine.css jasmine-extensions intense headless_reporter_result jasmine.HeadlessConsoleReporter jsDump beautify-html}
       end
+
+      def extension_filter
+        extensions = (%w{.js .css} + Sprockets.engine_extensions)
+
+        %r{(#{extensions.join('|')})$}
+      end
     end
 
     PLEASE_WAIT_IM_WORKING_TIME = 2
@@ -212,11 +219,17 @@ module Jasmine::Headless
     end
 
     def expanded_dir(path)
-      Dir[path].find_all { |file| file[extension_filter] }.collect { |file| File.expand_path(file) }.find_all { |path| File.file?(path) }
+      Dir[path].find_all { |file|
+        file[extension_filter] && !alert_if_bad_format?(file)
+      }.collect {
+        |file| File.expand_path(file)
+      }.find_all {
+        |path| File.file?(path)
+      }
     end
 
     def extension_filter
-      %r{(#{(%w{.js .css} + Sprockets.engine_extensions).join('|')})$}
+      self.class.extension_filter
     end
 
     def add_path(path, type)
diff --git a/spec/integration/sprockets_spec.rb b/spec/integration/sprockets_spec.rb
index 19f8cd6..10751cb 100644
--- a/spec/integration/sprockets_spec.rb
+++ b/spec/integration/sprockets_spec.rb
@@ -9,11 +9,15 @@ describe 'sprockets' do
       'vendor/assets/javascripts/jquery.js',
       'templates/that.jst.ejs',
       'templates/this.jst',
+      'things/jquery.string.js',
       'assets/things/required.js',
       'assets/things/code.js',
       'assets/things/subcode/more_code.js',
       'spec_helper.js',
       'spec/things/code_spec.js'
     )
+
+    files.lines.to_a.any? { |line| line['assets/jquery.string.js: unsupported format'] }.should be_false
   end
 end
+
diff --git a/spec/jasmine/with_sprockets_includes/assets/things/jquery.string.js b/spec/jasmine/with_sprockets_includes/assets/things/jquery.string.js
new file mode 100644
index 0000000..e69de29
diff --git a/spec/jasmine/with_sprockets_includes/assets/things/required.js b/spec/jasmine/with_sprockets_includes/assets/things/required.js
index 18241c9..9e80f9e 100644
--- a/spec/jasmine/with_sprockets_includes/assets/things/required.js
+++ b/spec/jasmine/with_sprockets_includes/assets/things/required.js
@@ -1,2 +1,3 @@
 //= require 'jquery'
+//= require 'things/jquery.string'
 
diff --git a/spec/lib/jasmine/headless/file_checker_spec.rb b/spec/lib/jasmine/headless/file_checker_spec.rb
index 571a73d..0e14a11 100644
--- a/spec/lib/jasmine/headless/file_checker_spec.rb
+++ b/spec/lib/jasmine/headless/file_checker_spec.rb
@@ -2,21 +2,24 @@ require 'spec_helper'
 
 describe Jasmine::Headless::FileChecker do
   include FakeFS::SpecHelpers
-  
+
   let(:test_class) do
     object = Object.new
     object.class.send(:include, Jasmine::Headless::FileChecker)
     object
   end
-  
+
   context "bad_format?" do
     it "should return false wth correct format" do
       test_class.bad_format?('foobar.js').should be_false
     end
+
     it "should return false wth wrong format" do
       test_class.bad_format?('foobar.js.erb').should be_true
     end
-  end
-  
 
+    it "should check for the whole extension" do
+      test_class.bad_format?('foobar.string.js').should be_false
+    end
+  end
 end
diff --git a/spec/lib/jasmine/headless/files_list_spec.rb b/spec/lib/jasmine/headless/files_list_spec.rb
index 111e281..d4037b8 100644
--- a/spec/lib/jasmine/headless/files_list_spec.rb
+++ b/spec/lib/jasmine/headless/files_list_spec.rb
@@ -204,15 +204,23 @@ describe Jasmine::Headless::FilesList do
       10.times do |index|
         File.open(File.join(dir, "file-#{index}.js"), 'wb')
       end
+
+      File.open(File.join(dir, 'file.js.erb'), 'wb')
+    end
+
+    before do
+      files_list.send(:add_files, [ '*' ], 'spec_files', [ dir ])
     end
 
     it 'should load spec files in a random order' do
-      files_list.send(:add_files, [ '*' ], 'spec_files', [ dir ])
-
       files_list.files.collect { |name| name[%r{\d+}] }.should == %w{6 7 1 0 5 3 4 8 2 9}
 
       FileUtils.rm_rf dir
     end
+
+    it 'should not load an excluded format' do
+      files_list.files.any? { |file| file['.erb'] }.should be_false
+    end
   end
 end