diff --git a/lib/jasmine/headless/files_list.rb b/lib/jasmine/headless/files_list.rb
index 4d45d51..8b4f51b 100644
--- a/lib/jasmine/headless/files_list.rb
+++ b/lib/jasmine/headless/files_list.rb
@@ -1,6 +1,7 @@
 require 'jasmine-core'
 require 'time'
 require 'multi_json'
+require 'set'
 
 module Jasmine::Headless
   class FilesList
@@ -35,6 +36,7 @@ module Jasmine::Headless
 
       @files = []
       @filtered_files = []
+      @checked_dependency = Set.new
 
       DEFAULT_FILES.each { |file| add_dependency('require', file, nil) }
 
@@ -96,7 +98,12 @@ module Jasmine::Headless
     end
 
     def add_dependencies(file, source_root)
-      TestFile.new(file, source_root).dependencies.each { |type, name| add_dependency(type, name, source_root) }
+      TestFile.new(file, source_root).dependencies.each do |type, name|
+        if !@checked_dependency.include?(name)
+          @checked_dependency << name
+          add_dependency(type, name, source_root)
+        end
+      end
     end
 
     EXTENSION_FILTER = %r{(#{(%w{.js .css} + Sprockets.engine_extensions).join('|')})$}
@@ -124,7 +131,11 @@ module Jasmine::Headless
           ok = (root == file)
           ok ||= File.basename(path.gsub("#{file}.", '')).split('.').all? { |part| ".#{part}"[EXTENSION_FILTER] }
 
-          return [ File.expand_path(path), File.expand_path(dir) ] if ok
+          expanded_path = File.expand_path(path)
+
+          if ok
+            return [ expanded_path, File.expand_path(dir) ]
+          end
         end
       end
 
diff --git a/lib/jasmine/headless/test_file.rb b/lib/jasmine/headless/test_file.rb
index 03fbda6..6e3bbb9 100644
--- a/lib/jasmine/headless/test_file.rb
+++ b/lib/jasmine/headless/test_file.rb
@@ -24,6 +24,8 @@ module Jasmine::Headless
       @dependencies = processor.directives.collect do |_, type, name|
         if name[%r{^\.}]
           name = File.expand_path(File.join(File.dirname(path), name)).gsub(%r{^#{source_root}/}, '')
+        else
+          raise Sprockets::ArgumentError.new("require_tree needs a relative path: ./#{path}") if type == 'require_tree'
         end
 
         [ type, name ]
diff --git a/spec/jasmine/with_sprockets_includes/assets/things/code.js b/spec/jasmine/with_sprockets_includes/assets/things/code.js
index 89bab5e..d437925 100644
--- a/spec/jasmine/with_sprockets_includes/assets/things/code.js
+++ b/spec/jasmine/with_sprockets_includes/assets/things/code.js
@@ -1,5 +1,5 @@
 //= require 'jquery'
-//= require_tree 'things/templates'
+//= require_tree './templates'
 //= require 'things/required'
 
 window.a = '1';
diff --git a/spec/lib/jasmine/headless/test_file_spec.rb b/spec/lib/jasmine/headless/test_file_spec.rb
index 6302fb2..9c47a20 100644
--- a/spec/lib/jasmine/headless/test_file_spec.rb
+++ b/spec/lib/jasmine/headless/test_file_spec.rb
@@ -82,9 +82,11 @@ describe Jasmine::Headless::TestFile do
   describe '#dependencies' do
     include FakeFS::SpecHelpers
 
+    let(:directive) { 'require' }
+
     before do
       FileUtils.mkdir_p File.dirname(path)
-      File.open(path, 'wb') { |fh| fh.print "//= require '#{req}'\njavascript" }
+      File.open(path, 'wb') { |fh| fh.print "//= #{directive} '#{req}'\njavascript" }
     end
 
     context 'absolute' do
@@ -92,7 +94,17 @@ describe Jasmine::Headless::TestFile do
 
       subject { file.dependencies }
 
-      it { should == [ [ 'require', req ] ] }
+      context 'require' do
+        it { should == [ [ 'require', req ] ] }
+      end
+
+      context 'require_tree' do
+        let(:directive) { 'require_tree' }
+
+        it 'should raise an error' do
+          expect { subject }.to raise_error(Sprockets::ArgumentError, /relative/)
+        end
+      end
     end
 
     context 'relative' do