diff --git a/cassette/cassette.go b/cassette/cassette.go
index 75358f1..a302800 100644
--- a/cassette/cassette.go
+++ b/cassette/cassette.go
@@ -186,16 +186,13 @@ func transformInterfacesInJSON(jsonString []byte) []byte {
 	return []byte(regex.ReplaceAllString(string(jsonString), `$1"$2",`))
 }
 
-// RecordNewTrackToCassette saves a new track using the specified details to a cassette.
-func RecordNewTrackToCassette(cassette *Cassette, req *Request, resp *Response, httpErr error) error {
-	// create track
-	t := NewTrack(req, resp, httpErr)
-
+// AddTrackToCassette saves a new track using the specified details to a cassette.
+func AddTrackToCassette(cassette *Cassette, aTrack *Track) error {
 	// mark track as replayed since it's coming from a live Request!
-	t.Replayed(true)
+	aTrack.Replayed(true)
 
 	// add track to cassette
-	cassette.AddTrack(t)
+	cassette.AddTrack(aTrack)
 
 	// save cassette
 	return cassette.save()
diff --git a/controlpanel.go b/controlpanel.go
index d413da4..7959fa6 100644
--- a/controlpanel.go
+++ b/controlpanel.go
@@ -24,7 +24,7 @@ func (controlPanel *ControlPanel) LoadCassette(cassetteName string) error {
 
 // LoadCassette into the VCR.
 func (controlPanel *ControlPanel) AddMutators(trackMutators ...TrackMutator) {
-	controlPanel.vcrTransport().addMutators(trackMutators...)
+	controlPanel.vcrTransport().AddMutators(trackMutators...)
 }
 
 // Player returns the http.Client that contains the VCR.
diff --git a/govcr_wb_test.go b/govcr_wb_test.go
index f3194ac..7280a16 100644
--- a/govcr_wb_test.go
+++ b/govcr_wb_test.go
@@ -61,9 +61,15 @@ func TestRoundTrip_SavesMutatedCassetteTracks(t *testing.T) {
 	}
 	require.EqualValues(t, expectedStats, actualStats)
 
-	// TODO now need to verify what is on the cassette has been mutated
+	err = vcr.LoadCassette(cassetteName)
+	assert.NoError(t, err)
 
-	t.Fatal("implement me - SHOULD TEST TRACKREPLAYMUTATOR")
+	for trackNum, aTrack := range vcr.vcrTransport().cassette.Tracks {
+		require.EqualValues(t, "GET has been mutated", aTrack.Request.Method, "track #%d", trackNum)
+		require.EqualValues(t, "200 OK has been mutated", aTrack.Response.Status, "track #%d", trackNum)
+		require.EqualValues(t, "ErrType was mutated", aTrack.ErrType, "track #%d", trackNum)
+		require.EqualValues(t, "ErrMsg was mutated", aTrack.ErrMsg, "track #%d", trackNum)
+	}
 }
 
 func makeHTTPCalls_WithSuccess(testServerURL string, vcr *ControlPanel, t *testing.T) stats.Stats {
diff --git a/pcb.go b/pcb.go
index f7fe1e2..3866665 100644
--- a/pcb.go
+++ b/pcb.go
@@ -52,6 +52,10 @@ func (pcbr *pcb) mutateTrack(t *cassette.Track) {
 	pcbr.trackRecordingMutators.Mutate(t)
 }
 
+func (pcbr *pcb) AddMutators(mutators ...TrackMutator) {
+	pcbr.trackRecordingMutators = pcbr.trackRecordingMutators.Add(mutators...)
+}
+
 // RequestMatcher is an interface that exposes the method to perform request comparison.
 // request comparison involves the HTTP request and the track request recorded on cassette.
 type RequestMatcher interface {
diff --git a/vcrsettings.go b/vcrsettings.go
index 47d2579..bee3fe8 100644
--- a/vcrsettings.go
+++ b/vcrsettings.go
@@ -45,7 +45,7 @@ func WithCassette(cassetteName string) Setting {
 // a cassette to load.
 func WithTrackRecordingMutators(trackRecordingMutators ...TrackMutator) Setting {
 	return func(vcrConfig *VCRSettings) {
-		vcrConfig.trackRecordingMutators.Add(trackRecordingMutators...)
+		vcrConfig.trackRecordingMutators = vcrConfig.trackRecordingMutators.Add(trackRecordingMutators...)
 	}
 }
 
diff --git a/vcrtransport.go b/vcrtransport.go
index 334dcd2..52c4ae2 100644
--- a/vcrtransport.go
+++ b/vcrtransport.go
@@ -37,8 +37,8 @@ func (t *vcrTransport) RoundTrip(httpRequest *http.Request) (*http.Response, err
 
 	newTrack := cassette.NewTrack(request, response, reqErr)
 	t.pcb.mutateTrack(newTrack)
-	if err := cassette.RecordNewTrackToCassette(t.cassette, request, response, reqErr); err != nil {
-		log.Printf("RoundTrip failed to RecordNewTrackToCassette: %v\n", err)
+	if err := cassette.AddTrackToCassette(t.cassette, newTrack); err != nil {
+		log.Printf("RoundTrip failed to AddTrackToCassette: %v\n", err)
 	}
 
 	return httpResponse, reqErr
@@ -68,8 +68,8 @@ func (t *vcrTransport) ejectCassette() {
 	t.cassette = nil
 }
 
-func (t *vcrTransport) addMutators(mutators ...TrackMutator) {
-	t.pcb.trackRecordingMutators.Add(mutators...)
+func (t *vcrTransport) AddMutators(mutators ...TrackMutator) {
+	t.pcb.AddMutators(mutators...)
 }
 
 func (t *vcrTransport) stats() *stats.Stats {