diff --git a/index.js b/index.js
index a7d0083..1bee463 100644
--- a/index.js
+++ b/index.js
@@ -198,22 +198,11 @@ function createRedirectDirectoryListener () {
 
     // send redirect response
     res.statusCode = 301
-    setHeaderIfNotSet(res, 'Content-Type', 'text/html; charset=UTF-8')
-    setHeaderIfNotSet(res, 'Content-Length', Buffer.byteLength(doc))
-    setHeaderIfNotSet(res, 'Content-Security-Policy', "default-src 'none'")
-    setHeaderIfNotSet(res, 'X-Content-Type-Options', 'nosniff')
-    setHeaderIfNotSet(res, 'Location', loc)
+    res.setHeader('Content-Type', 'text/html; charset=UTF-8')
+    res.setHeader('Content-Length', Buffer.byteLength(doc))
+    res.setHeader('Content-Security-Policy', "default-src 'none'")
+    res.setHeader('X-Content-Type-Options', 'nosniff')
+    res.setHeader('Location', loc)
     res.end(doc)
   }
 }
-
-/**
- * Set default value for the header only if it is not already set in the response
- * @private
- */
-
-function setHeaderIfNotSet (res, name, value) {
-  if (!res.hasHeader(name)) {
-    res.setHeader(name, value)
-  }
-}
diff --git a/test/test.js b/test/test.js
index c92ce00..9933eed 100644
--- a/test/test.js
+++ b/test/test.js
@@ -468,9 +468,6 @@ describe('serveStatic()', function () {
     before(function () {
       server = createServer(fixtures, null, function (req, res) {
         req.url = req.url.replace(/\/snow(\/|$)/, '/snow \u2603$1')
-        if (req.url.match(/\/pets/)) {
-          res.setHeader('Content-Security-Policy', "default-src 'self'")
-        }
       })
     })
 
@@ -510,20 +507,13 @@ describe('serveStatic()', function () {
         .expect(301, />Redirecting to \/snow%20%E2%98%83\/</, done)
     })
 
-    it('should respond with default Content-Security-Policy when header is not set', function (done) {
+    it('should respond with default Content-Security-Policy', function (done) {
       request(server)
         .get('/users')
         .expect('Content-Security-Policy', "default-src 'none'")
         .expect(301, done)
     })
 
-    it('should respond with custom Content-Security-Policy when header is set', function (done) {
-      request(server)
-        .get('/pets')
-        .expect('Content-Security-Policy', "default-src 'self'")
-        .expect(301, done)
-    })
-
     it('should not redirect incorrectly', function (done) {
       request(server)
         .get('/')