diff --git a/Makefile b/Makefile
index 4a4510b..c33ba3e 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@ lint: deps
 	@-echo "NOTE: some linters (gotype) require a recent 'go install'"
 	go get -u github.com/alecthomas/gometalinter
 	gometalinter --install --update
-	gometalinter --deadline=300s --disable=dupl --concurrency=2 ./...
+	gometalinter --deadline=300s --disable=dupl --concurrency=4
 
 goconvey:
 	@-killall goconvey
diff --git a/cassette.go b/cassette.go
index 6ed91e3..519ab08 100644
--- a/cassette.go
+++ b/cassette.go
@@ -224,10 +224,12 @@ type cassette struct {
 	removeTLS    bool
 }
 
-func NewCassette(name string, path string) *cassette {
+// newCassette creates a ready to use new cassette.
+func newCassette(name string, path string) *cassette {
 	return &cassette{Name: name, Path: path, trackSliceMutex: &sync.RWMutex{}}
 }
 
+// isLongPlay returns true if the cassette content is compressed.
 func (k7 *cassette) isLongPlay() bool {
 	return strings.HasSuffix(k7.Name, ".gz")
 }
@@ -428,7 +430,7 @@ func loadCassette(cassetteName, cassettePath string) (*cassette, error) {
 
 	// provide an empty cassette as a minimum
 	if k7 == nil {
-		k7 = NewCassette(cassetteName, cassettePath)
+		k7 = newCassette(cassetteName, cassettePath)
 	}
 
 	// initial stats
@@ -441,7 +443,7 @@ func loadCassette(cassetteName, cassettePath string) (*cassette, error) {
 func readCassetteFromFile(cassetteName, cassettePath string) (*cassette, error) {
 	filename := cassetteNameToFilename(cassetteName, cassettePath)
 
-	k7 := NewCassette(cassetteName, cassettePath)
+	k7 := newCassette(cassetteName, cassettePath)
 
 	data, err := ioutil.ReadFile(filename)
 	if os.IsNotExist(err) {
diff --git a/cassette_test.go b/cassette_test.go
index c35dead..0fbd564 100644
--- a/cassette_test.go
+++ b/cassette_test.go
@@ -65,7 +65,7 @@ func Test_cassette_gzipFilter(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			k7 := NewCassette(tt.fields.Name, tt.fields.Path)
+			k7 := newCassette(tt.fields.Name, tt.fields.Path)
 			k7.Tracks = tt.fields.Tracks
 			k7.tracksLoaded = tt.fields.stats.TracksLoaded
 
@@ -110,7 +110,7 @@ func Test_cassette_isLongPlay(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			k7 := NewCassette(tt.fields.Name, tt.fields.Path)
+			k7 := newCassette(tt.fields.Name, tt.fields.Path)
 			k7.Tracks = tt.fields.Tracks
 			k7.tracksLoaded = tt.fields.stats.TracksLoaded
 
@@ -163,7 +163,7 @@ func Test_cassette_gunzipFilter(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			k7 := NewCassette(tt.fields.Name, tt.fields.Path)
+			k7 := newCassette(tt.fields.Name, tt.fields.Path)
 			k7.Tracks = tt.fields.Tracks
 			k7.tracksLoaded = tt.fields.stats.TracksLoaded
 
@@ -280,7 +280,7 @@ func Test_cassette_addTrack(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			k7 := NewCassette(tt.name, tt.name)
+			k7 := newCassette(tt.name, tt.name)
 			k7.removeTLS = tt.fields.removeTLS
 
 			k7.addTrack(&tt.args.track)
diff --git a/vcr_transport_test.go b/vcr_transport_test.go
index 6258ed8..e4851ad 100644
--- a/vcr_transport_test.go
+++ b/vcr_transport_test.go
@@ -52,7 +52,7 @@ func Test_vcrTransport_RoundTrip_doesNotChangeLiveReqOrLiveResp(t *testing.T) {
 			Logger:           logger,
 			CassettePath:     "",
 		},
-		Cassette: NewCassette("", ""),
+		Cassette: newCassette("", ""),
 	}
 
 	req, err := http.NewRequest("GET", "https://example.com/path?query", toReadCloser([]byte("Lorem ipsum dolor sit amet")))