diff --git a/examples/fileserver/fileserver.go b/examples/fileserver/fileserver.go
index 1636d83..e91615b 100644
--- a/examples/fileserver/fileserver.go
+++ b/examples/fileserver/fileserver.go
@@ -9,14 +9,23 @@ import (
 )
 
 var (
-	addr = flag.String("addr", ":8080", "TCP address to listen to")
-	dir  = flag.String("dir", "/usr/share/nginx/html", "Directory to serve static files from")
+	addr               = flag.String("addr", ":8080", "TCP address to listen to")
+	compress           = flag.Bool("compress", false, "Enables transparent response compression if set to true")
+	dir                = flag.String("dir", "/usr/share/nginx/html", "Directory to serve static files from")
+	generateIndexPages = flag.Bool("generateIndexPages", true, "Whether to generate directory index pages")
 )
 
 func main() {
 	flag.Parse()
 
-	h := fasthttp.FSHandler(*dir, 0)
+	fs := &fasthttp.FS{
+		Root:               *dir,
+		IndexNames:         []string{"index.html"},
+		GenerateIndexPages: *generateIndexPages,
+		Compress:           *compress,
+	}
+	h := fs.NewRequestHandler()
+
 	if err := fasthttp.ListenAndServe(*addr, h); err != nil {
 		log.Fatalf("error in ListenAndServe: %s", err)
 	}
diff --git a/fs.go b/fs.go
index acafde9..1c89b6a 100644
--- a/fs.go
+++ b/fs.go
@@ -8,6 +8,7 @@ import (
 	"io"
 	"mime"
 	"os"
+	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
@@ -65,12 +66,35 @@ type FS struct {
 	// Path to the root directory to serve files from.
 	Root string
 
-	// Index pages for directories without index.html are automatically
-	// generated if set.
+	// List of index file names to try opening during directory access.
+	//
+	// For example:
+	//
+	//     * index.html
+	//     * index.htm
+	//     * my-super-index.xml
+	//
+	// By default the list is empty.
+	IndexNames []string
+
+	// Index pages for directories without files matching IndexNames
+	// are automatically generated if set.
 	//
 	// By default index pages aren't generated.
 	GenerateIndexPages bool
 
+	// Transparently compresses responses if set to true.
+	//
+	// The server tries minimizing CPU usage by caching compressed files.
+	// It adds FSCompressedFileSuffix suffix to the original file name and
+	// tries saving the resulting compressed file under the new file name.
+	// So it is advisable to give the server write access to Root
+	// and to all inner folders in order to minimze CPU usage when serving
+	// compressed responses.
+	//
+	// Transparent compression is disabled by default.
+	Compress bool
+
 	// Path rewriting function.
 	//
 	// By default request path is not modified.
@@ -84,9 +108,13 @@ type FS struct {
 	started bool
 }
 
+// FS adds this suffix to the original file names when trying to store
+// compressed file under the new file name. See FS.Compress for details.
+const FSCompressedFileSuffix = ".fasthttp.gz"
+
 // FSHandlerCacheDuration is the duration for caching open file handles
 // by FSHandler.
-const FSHandlerCacheDuration = 5 * time.Second
+const FSHandlerCacheDuration = 10 * time.Second
 
 // FSHandler returns request handler serving static files from
 // the given root folder.
@@ -113,6 +141,7 @@ const FSHandlerCacheDuration = 5 * time.Second
 func FSHandler(root string, stripSlashes int) RequestHandler {
 	fs := &FS{
 		Root:               root,
+		IndexNames:         []string{"index.html"},
 		GenerateIndexPages: true,
 		PathRewrite:        NewPathSlashesStripper(stripSlashes),
 	}
@@ -151,23 +180,22 @@ func (fs *FS) NewRequestHandler() RequestHandler {
 		cacheDuration = FSHandlerCacheDuration
 	}
 
-	pathRewrite := fs.PathRewrite
-	if pathRewrite == nil {
-		pathRewrite = NewPathSlashesStripper(0)
-	}
-
 	h := &fsHandler{
 		root:               root,
-		pathRewrite:        pathRewrite,
+		indexNames:         fs.IndexNames,
+		pathRewrite:        fs.PathRewrite,
 		generateIndexPages: fs.GenerateIndexPages,
+		compress:           fs.Compress,
 		cacheDuration:      cacheDuration,
 		cache:              make(map[string]*fsFile),
+		compressedCache:    make(map[string]*fsFile),
 	}
 
 	go func() {
+		var pendingFiles []*fsFile
 		for {
 			time.Sleep(cacheDuration / 2)
-			h.cleanCache()
+			pendingFiles = h.cleanCache(pendingFiles)
 		}
 	}()
 
@@ -176,13 +204,16 @@ func (fs *FS) NewRequestHandler() RequestHandler {
 
 type fsHandler struct {
 	root               string
+	indexNames         []string
 	pathRewrite        PathRewriteFunc
 	generateIndexPages bool
+	compress           bool
 	cacheDuration      time.Duration
 
-	cache        map[string]*fsFile
-	pendingFiles []*fsFile
-	cacheLock    sync.Mutex
+	cache           map[string]*fsFile
+	compressedCache map[string]*fsFile
+	pendingFiles    []*fsFile
+	cacheLock       sync.Mutex
 
 	smallFileReaderPool sync.Pool
 }
@@ -193,6 +224,7 @@ type fsFile struct {
 	dirIndex      []byte
 	contentType   string
 	contentLength int
+	compressed    bool
 
 	lastModified    time.Time
 	lastModifiedStr []byte
@@ -400,42 +432,60 @@ func (r *fsSmallFileReader) WriteTo(w io.Writer) (int64, error) {
 	return r.offset, err
 }
 
-func (h *fsHandler) cleanCache() {
-	t := time.Now()
+func (h *fsHandler) cleanCache(pendingFiles []*fsFile) []*fsFile {
+	var filesToRelease []*fsFile
+
 	h.cacheLock.Lock()
 
 	// Close files which couldn't be closed before due to non-zero
-	// readers count.
-	var pendingFiles []*fsFile
-	for _, ff := range h.pendingFiles {
+	// readers count on the previous run.
+	var remainingFiles []*fsFile
+	for _, ff := range pendingFiles {
 		if ff.readersCount > 0 {
-			pendingFiles = append(pendingFiles, ff)
+			remainingFiles = append(remainingFiles, ff)
 		} else {
-			ff.Release()
+			filesToRelease = append(filesToRelease, ff)
 		}
 	}
-	h.pendingFiles = pendingFiles
+	pendingFiles = remainingFiles
 
-	// Close stale file handles.
-	for k, ff := range h.cache {
-		if t.Sub(ff.t) > h.cacheDuration {
+	pendingFiles, filesToRelease = cleanCacheNolock(h.cache, pendingFiles, filesToRelease, h.cacheDuration)
+	pendingFiles, filesToRelease = cleanCacheNolock(h.compressedCache, pendingFiles, filesToRelease, h.cacheDuration)
+
+	h.cacheLock.Unlock()
+
+	for _, ff := range filesToRelease {
+		ff.Release()
+	}
+
+	return pendingFiles
+}
+
+func cleanCacheNolock(cache map[string]*fsFile, pendingFiles, filesToRelease []*fsFile, cacheDuration time.Duration) ([]*fsFile, []*fsFile) {
+	t := time.Now()
+	for k, ff := range cache {
+		if t.Sub(ff.t) > cacheDuration {
 			if ff.readersCount > 0 {
 				// There are pending readers on stale file handle,
 				// so we cannot close it. Put it into pendingFiles
 				// so it will be closed later.
-				h.pendingFiles = append(h.pendingFiles, ff)
+				pendingFiles = append(pendingFiles, ff)
 			} else {
-				ff.Release()
+				filesToRelease = append(filesToRelease, ff)
 			}
-			delete(h.cache, k)
+			delete(cache, k)
 		}
 	}
-
-	h.cacheLock.Unlock()
+	return pendingFiles, filesToRelease
 }
 
 func (h *fsHandler) handleRequest(ctx *RequestCtx) {
-	path := h.pathRewrite(ctx)
+	var path []byte
+	if h.pathRewrite != nil {
+		path = h.pathRewrite(ctx)
+	} else {
+		path = ctx.Path()
+	}
 	path = stripTrailingSlashes(path)
 
 	if n := bytes.IndexByte(path, 0); n >= 0 {
@@ -444,8 +494,15 @@ func (h *fsHandler) handleRequest(ctx *RequestCtx) {
 		return
 	}
 
+	mustCompress := false
+	fileCache := h.cache
+	if h.compress && ctx.Request.Header.HasAcceptEncodingBytes(strGzip) {
+		mustCompress = true
+		fileCache = h.compressedCache
+	}
+
 	h.cacheLock.Lock()
-	ff, ok := h.cache[string(path)]
+	ff, ok := fileCache[string(path)]
 	if ok {
 		ff.readersCount++
 	}
@@ -455,17 +512,12 @@ func (h *fsHandler) handleRequest(ctx *RequestCtx) {
 		pathStr := string(path)
 		filePath := h.root + pathStr
 		var err error
-		ff, err = h.openFSFile(filePath)
+		ff, err = h.openFSFile(filePath, mustCompress)
 		if err == errDirIndexRequired {
-			if !h.generateIndexPages {
-				ctx.Logger().Printf("An attempt to access directory without index page. Directory %q", filePath)
-				ctx.Error("Directory index is forbidden", StatusForbidden)
-				return
-			}
-			ff, err = h.createDirIndex(ctx.URI(), filePath)
+			ff, err = h.openIndexFile(ctx, filePath, mustCompress)
 			if err != nil {
-				ctx.Logger().Printf("Cannot create index for directory %q: %s", filePath, err)
-				ctx.Error("Cannot create directory index", StatusNotFound)
+				ctx.Logger().Printf("cannot open dir index %q: %s", filePath, err)
+				ctx.Error("Directory index is forbidden", StatusForbidden)
 				return
 			}
 		} else if err != nil {
@@ -475,9 +527,9 @@ func (h *fsHandler) handleRequest(ctx *RequestCtx) {
 		}
 
 		h.cacheLock.Lock()
-		ff1, ok := h.cache[pathStr]
+		ff1, ok := fileCache[pathStr]
 		if !ok {
-			h.cache[pathStr] = ff
+			fileCache[pathStr] = ff
 			ff.readersCount++
 		} else {
 			ff1.readersCount++
@@ -506,14 +558,37 @@ func (h *fsHandler) handleRequest(ctx *RequestCtx) {
 		return
 	}
 
+	if ff.compressed {
+		ctx.Response.Header.SetCanonical(strContentEncoding, strGzip)
+	}
 	ctx.Response.Header.SetCanonical(strLastModified, ff.lastModifiedStr)
 	ctx.SetBodyStream(r, ff.contentLength)
 	ctx.SetContentType(ff.contentType)
+	ctx.SetStatusCode(StatusOK)
+}
+
+func (h *fsHandler) openIndexFile(ctx *RequestCtx, dirPath string, mustCompress bool) (*fsFile, error) {
+	for _, indexName := range h.indexNames {
+		indexFilePath := dirPath + "/" + indexName
+		ff, err := h.openFSFile(indexFilePath, mustCompress)
+		if err == nil {
+			return ff, nil
+		}
+		if !os.IsNotExist(err) {
+			return nil, fmt.Errorf("cannot open file %q: %s", indexFilePath, err)
+		}
+	}
+
+	if !h.generateIndexPages {
+		return nil, fmt.Errorf("cannot access directory without index page. Directory %q", dirPath)
+	}
+
+	return h.createDirIndex(ctx.URI(), dirPath, mustCompress)
 }
 
 var errDirIndexRequired = errors.New("directory index required")
 
-func (h *fsHandler) createDirIndex(base *URI, filePath string) (*fsFile, error) {
+func (h *fsHandler) createDirIndex(base *URI, dirPath string, mustCompress bool) (*fsFile, error) {
 	var buf bytes.Buffer
 	w := &buf
 
@@ -530,7 +605,7 @@ func (h *fsHandler) createDirIndex(base *URI, filePath string) (*fsFile, error)
 		fmt.Fprintf(w, `<li><a href="%s" class="dir">..</a></li>`, parentPathEscaped)
 	}
 
-	f, err := os.Open(filePath)
+	f, err := os.Open(dirPath)
 	if err != nil {
 		return nil, err
 	}
@@ -569,64 +644,198 @@ func (h *fsHandler) createDirIndex(base *URI, filePath string) (*fsFile, error)
 	}
 
 	fmt.Fprintf(w, "</ul></body></html>")
-	dirIndex := w.Bytes()
 
+	if mustCompress {
+		var zbuf bytes.Buffer
+		zw := acquireGzipWriter(&zbuf, CompressDefaultCompression)
+		_, err = io.Copy(zw, &buf)
+		releaseGzipWriter(zw)
+		if err != nil {
+			return nil, fmt.Errorf("error when compressing automatically generated index for directory %q: %s", dirPath, err)
+		}
+		w = &zbuf
+	}
+
+	dirIndex := w.Bytes()
 	lastModified := time.Now()
 	ff := &fsFile{
 		h:               h,
 		dirIndex:        dirIndex,
 		contentType:     "text/html; charset=utf-8",
 		contentLength:   len(dirIndex),
+		compressed:      mustCompress,
 		lastModified:    lastModified,
 		lastModifiedStr: AppendHTTPDate(nil, lastModified),
+
+		t: lastModified,
 	}
 	return ff, nil
 }
 
-func (h *fsHandler) openFSFile(filePath string) (*fsFile, error) {
+const fsMinCompressRatio = 0.9
+
+func (h *fsHandler) compressAndOpenFSFile(filePath string) (*fsFile, error) {
 	f, err := os.Open(filePath)
 	if err != nil {
 		return nil, err
 	}
 
-	fileStat, err := f.Stat()
+	fileInfo, err := f.Stat()
 	if err != nil {
 		f.Close()
+		return nil, fmt.Errorf("cannot obtain info for file %q: %s", filePath, err)
+	}
+
+	if fileInfo.IsDir() {
+		f.Close()
+		return nil, errDirIndexRequired
+	}
+
+	if !isFileCompressible(f, fsMinCompressRatio) {
+		return h.newFSFile(f, fileInfo, false)
+	}
+
+	compressedFilePath := filePath + FSCompressedFileSuffix
+	absPath, err := filepath.Abs(compressedFilePath)
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("cannot determine absolute path for %q: %s", compressedFilePath, err)
+	}
+
+	flock := getFileLock(absPath)
+	flock.Lock()
+	ff, err := h.compressFileNolock(f, fileInfo, filePath, compressedFilePath)
+	flock.Unlock()
+
+	return ff, err
+}
+
+func (h *fsHandler) compressFileNolock(f *os.File, fileInfo os.FileInfo, filePath, compressedFilePath string) (*fsFile, error) {
+	// Attempt to open compressed file created by another concurrent
+	// goroutine.
+	// It is safe opening such a file, since the file creation
+	// is guarded by file mutex - see getFileLock call.
+	if _, err := os.Stat(compressedFilePath); err == nil {
+		f.Close()
+		return h.newCompressedFSFile(compressedFilePath)
+	}
+
+	// Create temporary file, so concurrent goroutines don't use
+	// it until it is created.
+	tmpFilePath := compressedFilePath + ".tmp"
+	zf, err := os.Create(tmpFilePath)
+	if err != nil {
+		if !os.IsPermission(err) {
+			f.Close()
+			return nil, fmt.Errorf("cannot create temporary file %q: %s", tmpFilePath, err)
+		}
+
+		// No permission for compressed file creation. Just return uncompressed file
+		return h.newFSFile(f, fileInfo, false)
+	}
+
+	zw := acquireGzipWriter(zf, CompressDefaultCompression)
+	_, err = io.Copy(zw, f)
+	if err1 := zw.Flush(); err == nil {
+		err = err1
+	}
+	releaseGzipWriter(zw)
+	zf.Close()
+	f.Close()
+	if err != nil {
+		return nil, fmt.Errorf("error when compressing file %q to %q: %s", filePath, tmpFilePath, err)
+	}
+	if err = os.Chtimes(tmpFilePath, time.Now(), fileInfo.ModTime()); err != nil {
+		return nil, fmt.Errorf("cannot change modification time to %s for tmp file %q: %s",
+			fileInfo.ModTime(), tmpFilePath, err)
+	}
+	if err = os.Rename(tmpFilePath, compressedFilePath); err != nil {
+		return nil, fmt.Errorf("cannot move compressed file from %q to %q: %s", tmpFilePath, compressedFilePath, err)
+	}
+	return h.newCompressedFSFile(compressedFilePath)
+}
+
+func (h *fsHandler) newCompressedFSFile(filePath string) (*fsFile, error) {
+	f, err := os.Open(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("cannot open compressed file %q: %s", filePath, err)
+	}
+	fileInfo, err := f.Stat()
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("cannot obtain info for compressed file %q: %s", filePath, err)
+	}
+	return h.newFSFile(f, fileInfo, true)
+}
+
+func (h *fsHandler) openFSFile(filePath string, mustCompress bool) (*fsFile, error) {
+	filePathOriginal := filePath
+	if mustCompress {
+		filePath += FSCompressedFileSuffix
+	}
+
+	f, err := os.Open(filePath)
+	if err != nil {
+		if mustCompress && os.IsNotExist(err) {
+			return h.compressAndOpenFSFile(filePathOriginal)
+		}
 		return nil, err
 	}
 
-	if fileStat.IsDir() {
+	fileInfo, err := f.Stat()
+	if err != nil {
 		f.Close()
+		return nil, fmt.Errorf("cannot obtain info for file %q: %s", filePath, err)
+	}
 
-		indexPath := filePath + "/index.html"
-		ff, err := h.openFSFile(indexPath)
-		if err == nil {
-			return ff, nil
-		}
-		if !os.IsNotExist(err) {
-			return nil, err
+	if fileInfo.IsDir() {
+		f.Close()
+		if mustCompress {
+			return nil, fmt.Errorf("directory with unexpected suffix found: %q. Suffix: %q", filePath, FSCompressedFileSuffix)
 		}
 		return nil, errDirIndexRequired
 	}
 
-	n := fileStat.Size()
+	if mustCompress {
+		fileInfoOriginal, err := os.Stat(filePathOriginal)
+		if err != nil {
+			f.Close()
+			return nil, fmt.Errorf("cannot obtain info for original file %q: %s", filePathOriginal, err)
+		}
+
+		if fileInfoOriginal.ModTime() != fileInfo.ModTime() {
+			// The compressed file became stale. Re-create it.
+			f.Close()
+			os.Remove(filePath)
+			return h.compressAndOpenFSFile(filePathOriginal)
+		}
+	}
+
+	return h.newFSFile(f, fileInfo, mustCompress)
+}
+
+func (h *fsHandler) newFSFile(f *os.File, fileInfo os.FileInfo, compressed bool) (*fsFile, error) {
+	n := fileInfo.Size()
 	contentLength := int(n)
 	if n != int64(contentLength) {
 		f.Close()
 		return nil, fmt.Errorf("too big file: %d bytes", n)
 	}
 
-	ext := fileExtension(filePath)
+	ext := fileExtension(fileInfo.Name(), compressed)
 	contentType := mime.TypeByExtension(ext)
 
-	lastModified := fileStat.ModTime()
+	lastModified := fileInfo.ModTime()
 	ff := &fsFile{
 		h:               h,
 		f:               f,
 		contentType:     contentType,
 		contentLength:   contentLength,
+		compressed:      compressed,
 		lastModified:    lastModified,
 		lastModifiedStr: AppendHTTPDate(nil, lastModified),
+
+		t: time.Now(),
 	}
 	return ff, nil
 }
@@ -654,7 +863,10 @@ func stripTrailingSlashes(path []byte) []byte {
 	return path
 }
 
-func fileExtension(path string) string {
+func fileExtension(path string, compressed bool) string {
+	if compressed && strings.HasSuffix(path, FSCompressedFileSuffix) {
+		path = path[:len(path)-len(FSCompressedFileSuffix)]
+	}
 	n := strings.LastIndexByte(path, '.')
 	if n < 0 {
 		return ""
@@ -678,3 +890,19 @@ func fsLastModified(path string) (time.Time, error) {
 func fsModTime(t time.Time) time.Time {
 	return t.In(gmtLocation).Truncate(time.Second)
 }
+
+var (
+	filesLockMap     = make(map[string]*sync.Mutex)
+	filesLockMapLock sync.Mutex
+)
+
+func getFileLock(absPath string) *sync.Mutex {
+	filesLockMapLock.Lock()
+	flock := filesLockMap[absPath]
+	if flock == nil {
+		flock = &sync.Mutex{}
+		filesLockMap[absPath] = flock
+	}
+	filesLockMapLock.Unlock()
+	return flock
+}
diff --git a/fs_test.go b/fs_test.go
index c757e35..c3712f8 100644
--- a/fs_test.go
+++ b/fs_test.go
@@ -1,7 +1,9 @@
 package fasthttp
 
 import (
+	"bufio"
 	"bytes"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"sort"
@@ -9,6 +11,115 @@ import (
 	"time"
 )
 
+func TestFSCompressConcurrent(t *testing.T) {
+	fs := &FS{
+		Root:               ".",
+		GenerateIndexPages: true,
+		Compress:           true,
+	}
+	h := fs.NewRequestHandler()
+
+	concurrency := 4
+	ch := make(chan struct{}, concurrency)
+	for i := 0; i < concurrency; i++ {
+		go func() {
+			for j := 0; j < 10; j++ {
+				testFSCompress(t, h, "/fs.go")
+				testFSCompress(t, h, "/")
+				testFSCompress(t, h, "/README.md")
+			}
+			ch <- struct{}{}
+		}()
+	}
+
+	for i := 0; i < concurrency; i++ {
+		select {
+		case <-ch:
+		case <-time.After(time.Second):
+			t.Fatalf("timeout")
+		}
+	}
+}
+
+func TestFSCompressSingleThread(t *testing.T) {
+	fs := &FS{
+		Root:               ".",
+		GenerateIndexPages: true,
+		Compress:           true,
+	}
+	h := fs.NewRequestHandler()
+
+	testFSCompress(t, h, "/fs.go")
+	testFSCompress(t, h, "/")
+	testFSCompress(t, h, "/README.md")
+}
+
+func testFSCompress(t *testing.T, h RequestHandler, filePath string) {
+	var ctx RequestCtx
+	ctx.Init(&Request{}, nil, nil)
+
+	// request uncompressed file
+	ctx.Request.Reset()
+	ctx.Request.SetRequestURI(filePath)
+	h(&ctx)
+
+	var resp Response
+	s := ctx.Response.String()
+	br := bufio.NewReader(bytes.NewBufferString(s))
+	if err := resp.Read(br); err != nil {
+		t.Fatalf("unexpected error: %s. filePath=%q", err, filePath)
+	}
+	if resp.StatusCode() != StatusOK {
+		t.Fatalf("unexpected status code: %d. Expecting %d. filePath=%q", resp.StatusCode(), StatusOK, filePath)
+	}
+	ce := resp.Header.Peek("Content-Encoding")
+	if string(ce) != "" {
+		t.Fatalf("unexpected content-encoding %q. Expecting empty string. filePath=%q", ce, filePath)
+	}
+	body := string(resp.Body())
+
+	// request compressed file
+	ctx.Request.Reset()
+	ctx.Request.SetRequestURI(filePath)
+	ctx.Request.Header.Set("Accept-Encoding", "gzip")
+	h(&ctx)
+	s = ctx.Response.String()
+	br = bufio.NewReader(bytes.NewBufferString(s))
+	if err := resp.Read(br); err != nil {
+		t.Fatalf("unexpected error: %s. filePath=%q", err, filePath)
+	}
+	if resp.StatusCode() != StatusOK {
+		t.Fatalf("unexpected status code: %d. Expecting %d. filePath=%q", resp.StatusCode(), StatusOK, filePath)
+	}
+	ce = resp.Header.Peek("Content-Encoding")
+	if string(ce) != "gzip" {
+		t.Fatalf("unexpected content-encoding %q. Expecting %q. filePath=%q", ce, "gzip", filePath)
+	}
+	zbody, err := resp.BodyGunzip()
+	if err != nil {
+		t.Fatalf("unexpected error when gunzipping response body: %s. filePath=%q", err, filePath)
+	}
+	if string(zbody) != body {
+		t.Fatalf("unexpected body %q. Expected %q. FilePath=%q", zbody, body, filePath)
+	}
+}
+
+func TestFileLock(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		filePath := fmt.Sprintf("foo/bar/%d.jpg", i)
+		lock := getFileLock(filePath)
+		lock.Lock()
+		lock.Unlock()
+	}
+
+	for i := 0; i < 10; i++ {
+		filePath := fmt.Sprintf("foo/bar/%d.jpg", i)
+		lock := getFileLock(filePath)
+		lock.Lock()
+		lock.Unlock()
+	}
+}
+
 func TestFSHandlerSingleThread(t *testing.T) {
 	requestHandler := FSHandler(".", 0)
 
@@ -151,15 +262,21 @@ func testStripPathSlashes(t *testing.T, path string, stripSlashes int, expectedP
 }
 
 func TestFileExtension(t *testing.T) {
-	testFileExtension(t, "foo.bar", ".bar")
-	testFileExtension(t, "foobar", "")
-	testFileExtension(t, "foo.bar.baz", ".baz")
-	testFileExtension(t, "", "")
-	testFileExtension(t, "/a/b/c.d/efg.jpg", ".jpg")
+	testFileExtension(t, "foo.bar", false, ".bar")
+	testFileExtension(t, "foobar", false, "")
+	testFileExtension(t, "foo.bar.baz", false, ".baz")
+	testFileExtension(t, "", false, "")
+	testFileExtension(t, "/a/b/c.d/efg.jpg", false, ".jpg")
+
+	testFileExtension(t, "foo.bar", true, ".bar")
+	testFileExtension(t, "foobar.fasthttp.gz", true, "")
+	testFileExtension(t, "foo.bar.baz.fasthttp.gz", true, ".baz")
+	testFileExtension(t, "", true, "")
+	testFileExtension(t, "/a/b/c.d/efg.jpg.fasthttp.gz", true, ".jpg")
 }
 
-func testFileExtension(t *testing.T, path, expectedExt string) {
-	ext := fileExtension(path)
+func testFileExtension(t *testing.T, path string, compressed bool, expectedExt string) {
+	ext := fileExtension(path, compressed)
 	if ext != expectedExt {
 		t.Fatalf("unexpected file extension for file %q: %q. Expecting %q", path, ext, expectedExt)
 	}