diff --git a/lib/rack/sendfile.rb b/lib/rack/sendfile.rb
index 75ccbf836..c82145ae0 100644
--- a/lib/rack/sendfile.rb
+++ b/lib/rack/sendfile.rb
@@ -105,6 +105,7 @@ def call(env)
         when 'X-Accel-Redirect'
           path = F.expand_path(body.to_path)
           if url = map_accel_path(env, path)
+            headers['Content-Length'] = '0'
             headers[type] = url
             body = []
           else
diff --git a/test/spec_sendfile.rb b/test/spec_sendfile.rb
index 84517e7ef..de4ae7ac9 100644
--- a/test/spec_sendfile.rb
+++ b/test/spec_sendfile.rb
@@ -40,6 +40,7 @@ def request(headers={})
     request 'HTTP_X_SENDFILE_TYPE' => 'X-Sendfile' do |response|
       response.should.be.ok
       response.body.should.be.empty
+      response.headers['Content-Length'].should == '0'
       response.headers['X-Sendfile'].should.equal '/tmp/hello.txt'
     end
   end
@@ -48,6 +49,7 @@ def request(headers={})
     request 'HTTP_X_SENDFILE_TYPE' => 'X-Lighttpd-Send-File' do |response|
       response.should.be.ok
       response.body.should.be.empty
+      response.headers['Content-Length'].should == '0'
       response.headers['X-Lighttpd-Send-File'].should.equal '/tmp/hello.txt'
     end
   end
@@ -60,6 +62,7 @@ def request(headers={})
     request headers do |response|
       response.should.be.ok
       response.body.should.be.empty
+      response.headers['Content-Length'].should == '0'
       response.headers['X-Accel-Redirect'].should.equal '/foo/bar/hello.txt'
     end
   end