diff --git a/codec.go b/codec.go
new file mode 100644
index 0000000..be7e6cb
--- /dev/null
+++ b/codec.go
@@ -0,0 +1,49 @@
+package scs
+
+import (
+	"bytes"
+	"encoding/gob"
+	"time"
+)
+
+// Codec is the interface for encoding/decoding session data to and from a byte
+// slice for use by the session store.
+type Codec interface {
+	Encode(deadline time.Time, values map[string]interface{}) ([]byte, error)
+	Decode([]byte) (deadline time.Time, values map[string]interface{}, err error)
+}
+
+type gobCodec struct{}
+
+func (gobCodec) Encode(deadline time.Time, values map[string]interface{}) ([]byte, error) {
+	aux := &struct {
+		Deadline time.Time
+		Values   map[string]interface{}
+	}{
+		Deadline: deadline,
+		Values:   values,
+	}
+
+	var b bytes.Buffer
+	err := gob.NewEncoder(&b).Encode(&aux)
+	if err != nil {
+		return nil, err
+	}
+
+	return b.Bytes(), nil
+}
+
+func (gobCodec) Decode(b []byte) (time.Time, map[string]interface{}, error) {
+	aux := &struct {
+		Deadline time.Time
+		Values   map[string]interface{}
+	}{}
+
+	r := bytes.NewReader(b)
+	err := gob.NewDecoder(r).Decode(&aux)
+	if err != nil {
+		return time.Time{}, nil, err
+	}
+
+	return aux.Deadline, aux.Values, nil
+}
diff --git a/data.go b/data.go
index e4fe95b..c18bfdc 100644
--- a/data.go
+++ b/data.go
@@ -1,11 +1,9 @@
 package scs
 
 import (
-	"bytes"
 	"context"
 	"crypto/rand"
 	"encoding/base64"
-	"encoding/gob"
 	"fmt"
 	"sort"
 	"sync"
@@ -30,18 +28,18 @@ const (
 )
 
 type sessionData struct {
-	Deadline time.Time // Exported for gob encoding.
+	deadline time.Time
 	status   Status
 	token    string
-	Values   map[string]interface{} // Exported for gob encoding.
+	values   map[string]interface{}
 	mu       sync.Mutex
 }
 
 func newSessionData(lifetime time.Duration) *sessionData {
 	return &sessionData{
-		Deadline: time.Now().Add(lifetime).UTC(),
+		deadline: time.Now().Add(lifetime).UTC(),
 		status:   Unmodified,
-		Values:   make(map[string]interface{}),
+		values:   make(map[string]interface{}),
 	}
 }
 
@@ -71,7 +69,7 @@ func (s *SessionManager) Load(ctx context.Context, token string) (context.Contex
 		status: Unmodified,
 		token:  token,
 	}
-	err = sd.decode(b)
+	sd.deadline, sd.values, err = s.Codec.Decode(b)
 	if err != nil {
 		return nil, err
 	}
@@ -104,12 +102,12 @@ func (s *SessionManager) Commit(ctx context.Context) (string, time.Time, error)
 		}
 	}
 
-	b, err := sd.encode()
+	b, err := s.Codec.Encode(sd.deadline, sd.values)
 	if err != nil {
 		return "", time.Time{}, err
 	}
 
-	expiry := sd.Deadline
+	expiry := sd.deadline
 	if s.IdleTimeout > 0 {
 		ie := time.Now().Add(s.IdleTimeout)
 		if ie.Before(expiry) {
@@ -143,9 +141,9 @@ func (s *SessionManager) Destroy(ctx context.Context) error {
 
 	// Reset everything else to defaults.
 	sd.token = ""
-	sd.Deadline = time.Now().Add(s.Lifetime).UTC()
-	for key := range sd.Values {
-		delete(sd.Values, key)
+	sd.deadline = time.Now().Add(s.Lifetime).UTC()
+	for key := range sd.values {
+		delete(sd.values, key)
 	}
 
 	return nil
@@ -158,7 +156,7 @@ func (s *SessionManager) Put(ctx context.Context, key string, val interface{}) {
 	sd := s.getSessionDataFromContext(ctx)
 
 	sd.mu.Lock()
-	sd.Values[key] = val
+	sd.values[key] = val
 	sd.status = Modified
 	sd.mu.Unlock()
 }
@@ -180,7 +178,7 @@ func (s *SessionManager) Get(ctx context.Context, key string) interface{} {
 	sd.mu.Lock()
 	defer sd.mu.Unlock()
 
-	return sd.Values[key]
+	return sd.values[key]
 }
 
 // Pop acts like a one-time Get. It returns the value for a given key from the
@@ -193,11 +191,11 @@ func (s *SessionManager) Pop(ctx context.Context, key string) interface{} {
 	sd.mu.Lock()
 	defer sd.mu.Unlock()
 
-	val, exists := sd.Values[key]
+	val, exists := sd.values[key]
 	if !exists {
 		return nil
 	}
-	delete(sd.Values, key)
+	delete(sd.values, key)
 	sd.status = Modified
 
 	return val
@@ -212,12 +210,12 @@ func (s *SessionManager) Remove(ctx context.Context, key string) {
 	sd.mu.Lock()
 	defer sd.mu.Unlock()
 
-	_, exists := sd.Values[key]
+	_, exists := sd.values[key]
 	if !exists {
 		return
 	}
 
-	delete(sd.Values, key)
+	delete(sd.values, key)
 	sd.status = Modified
 }
 
@@ -230,12 +228,12 @@ func (s *SessionManager) Clear(ctx context.Context) error {
 	sd.mu.Lock()
 	defer sd.mu.Unlock()
 
-	if len(sd.Values) == 0 {
+	if len(sd.values) == 0 {
 		return nil
 	}
 
-	for key := range sd.Values {
-		delete(sd.Values, key)
+	for key := range sd.values {
+		delete(sd.values, key)
 	}
 	sd.status = Modified
 	return nil
@@ -246,7 +244,7 @@ func (s *SessionManager) Exists(ctx context.Context, key string) bool {
 	sd := s.getSessionDataFromContext(ctx)
 
 	sd.mu.Lock()
-	_, exists := sd.Values[key]
+	_, exists := sd.values[key]
 	sd.mu.Unlock()
 
 	return exists
@@ -259,9 +257,9 @@ func (s *SessionManager) Keys(ctx context.Context) []string {
 	sd := s.getSessionDataFromContext(ctx)
 
 	sd.mu.Lock()
-	keys := make([]string, len(sd.Values))
+	keys := make([]string, len(sd.values))
 	i := 0
-	for key := range sd.Values {
+	for key := range sd.values {
 		keys[i] = key
 		i++
 	}
@@ -298,7 +296,7 @@ func (s *SessionManager) RenewToken(ctx context.Context) error {
 	}
 
 	sd.token = newToken
-	sd.Deadline = time.Now().Add(s.Lifetime).UTC()
+	sd.deadline = time.Now().Add(s.Lifetime).UTC()
 	sd.status = Modified
 
 	return nil
@@ -477,21 +475,6 @@ func (s *SessionManager) getSessionDataFromContext(ctx context.Context) *session
 	return c
 }
 
-func (sd *sessionData) encode() ([]byte, error) {
-	var b bytes.Buffer
-	err := gob.NewEncoder(&b).Encode(sd)
-	if err != nil {
-		return nil, err
-	}
-
-	return b.Bytes(), nil
-}
-
-func (sd *sessionData) decode(b []byte) error {
-	r := bytes.NewReader(b)
-	return gob.NewDecoder(r).Decode(sd)
-}
-
 func generateToken() (string, error) {
 	b := make([]byte, 32)
 	_, err := rand.Read(b)
diff --git a/data_test.go b/data_test.go
index ec7c220..a50b6b9 100644
--- a/data_test.go
+++ b/data_test.go
@@ -26,8 +26,8 @@ func TestPut(t *testing.T) {
 
 	s.Put(ctx, "foo", "bar")
 
-	if sd.Values["foo"] != "bar" {
-		t.Errorf("got %q: expected %q", sd.Values["foo"], "bar")
+	if sd.values["foo"] != "bar" {
+		t.Errorf("got %q: expected %q", sd.values["foo"], "bar")
 	}
 
 	if sd.status != Modified {
@@ -38,7 +38,7 @@ func TestPut(t *testing.T) {
 func TestGet(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
+	sd.values["foo"] = "bar"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	str, ok := s.Get(ctx, "foo").(string)
@@ -54,7 +54,7 @@ func TestGet(t *testing.T) {
 func TestPop(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
+	sd.values["foo"] = "bar"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	str, ok := s.Pop(ctx, "foo").(string)
@@ -66,7 +66,7 @@ func TestPop(t *testing.T) {
 		t.Errorf("got %q: expected %q", str, "bar")
 	}
 
-	_, ok = sd.Values["foo"]
+	_, ok = sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
@@ -79,13 +79,13 @@ func TestPop(t *testing.T) {
 func TestRemove(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
+	sd.values["foo"] = "bar"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	s.Remove(ctx, "foo")
 
-	if sd.Values["foo"] != nil {
-		t.Errorf("got %v: expected %v", sd.Values["foo"], nil)
+	if sd.values["foo"] != nil {
+		t.Errorf("got %v: expected %v", sd.values["foo"], nil)
 	}
 
 	if sd.status != Modified {
@@ -96,18 +96,18 @@ func TestRemove(t *testing.T) {
 func TestClear(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
-	sd.Values["baz"] = "boz"
+	sd.values["foo"] = "bar"
+	sd.values["baz"] = "boz"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	s.Clear(ctx)
 
-	if sd.Values["foo"] != nil {
-		t.Errorf("got %v: expected %v", sd.Values["foo"], nil)
+	if sd.values["foo"] != nil {
+		t.Errorf("got %v: expected %v", sd.values["foo"], nil)
 	}
 
-	if sd.Values["baz"] != nil {
-		t.Errorf("got %v: expected %v", sd.Values["baz"], nil)
+	if sd.values["baz"] != nil {
+		t.Errorf("got %v: expected %v", sd.values["baz"], nil)
 	}
 
 	if sd.status != Modified {
@@ -118,7 +118,7 @@ func TestClear(t *testing.T) {
 func TestExists(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
+	sd.values["foo"] = "bar"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	if !s.Exists(ctx, "foo") {
@@ -133,8 +133,8 @@ func TestExists(t *testing.T) {
 func TestKeys(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
-	sd.Values["woo"] = "waa"
+	sd.values["foo"] = "bar"
+	sd.values["woo"] = "waa"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	keys := s.Keys(ctx)
@@ -146,7 +146,7 @@ func TestKeys(t *testing.T) {
 func TestGetString(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
+	sd.values["foo"] = "bar"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	str := s.GetString(ctx, "foo")
@@ -163,7 +163,7 @@ func TestGetString(t *testing.T) {
 func TestGetBool(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = true
+	sd.values["foo"] = true
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	b := s.GetBool(ctx, "foo")
@@ -180,7 +180,7 @@ func TestGetBool(t *testing.T) {
 func TestGetInt(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = 123
+	sd.values["foo"] = 123
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	i := s.GetInt(ctx, "foo")
@@ -197,7 +197,7 @@ func TestGetInt(t *testing.T) {
 func TestGetFloat(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = 123.456
+	sd.values["foo"] = 123.456
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	f := s.GetFloat(ctx, "foo")
@@ -214,7 +214,7 @@ func TestGetFloat(t *testing.T) {
 func TestGetBytes(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = []byte("bar")
+	sd.values["foo"] = []byte("bar")
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	b := s.GetBytes(ctx, "foo")
@@ -233,7 +233,7 @@ func TestGetTime(t *testing.T) {
 
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = now
+	sd.values["foo"] = now
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	tm := s.GetTime(ctx, "foo")
@@ -250,7 +250,7 @@ func TestGetTime(t *testing.T) {
 func TestPopString(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = "bar"
+	sd.values["foo"] = "bar"
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	str := s.PopString(ctx, "foo")
@@ -258,7 +258,7 @@ func TestPopString(t *testing.T) {
 		t.Errorf("got %q: expected %q", str, "bar")
 	}
 
-	_, ok := sd.Values["foo"]
+	_, ok := sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
@@ -276,7 +276,7 @@ func TestPopString(t *testing.T) {
 func TestPopBool(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = true
+	sd.values["foo"] = true
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	b := s.PopBool(ctx, "foo")
@@ -284,7 +284,7 @@ func TestPopBool(t *testing.T) {
 		t.Errorf("got %v: expected %v", b, true)
 	}
 
-	_, ok := sd.Values["foo"]
+	_, ok := sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
@@ -302,7 +302,7 @@ func TestPopBool(t *testing.T) {
 func TestPopInt(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = 123
+	sd.values["foo"] = 123
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	i := s.PopInt(ctx, "foo")
@@ -310,7 +310,7 @@ func TestPopInt(t *testing.T) {
 		t.Errorf("got %d: expected %d", i, 123)
 	}
 
-	_, ok := sd.Values["foo"]
+	_, ok := sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
@@ -328,7 +328,7 @@ func TestPopInt(t *testing.T) {
 func TestPopFloat(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = 123.456
+	sd.values["foo"] = 123.456
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	f := s.PopFloat(ctx, "foo")
@@ -336,7 +336,7 @@ func TestPopFloat(t *testing.T) {
 		t.Errorf("got %f: expected %f", f, 123.456)
 	}
 
-	_, ok := sd.Values["foo"]
+	_, ok := sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
@@ -354,14 +354,14 @@ func TestPopFloat(t *testing.T) {
 func TestPopBytes(t *testing.T) {
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = []byte("bar")
+	sd.values["foo"] = []byte("bar")
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	b := s.PopBytes(ctx, "foo")
 	if !bytes.Equal(b, []byte("bar")) {
 		t.Errorf("got %v: expected %v", b, []byte("bar"))
 	}
-	_, ok := sd.Values["foo"]
+	_, ok := sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
@@ -380,7 +380,7 @@ func TestPopTime(t *testing.T) {
 	now := time.Now()
 	s := NewSession()
 	sd := newSessionData(time.Hour)
-	sd.Values["foo"] = now
+	sd.values["foo"] = now
 	ctx := s.addSessionDataToContext(context.Background(), sd)
 
 	tm := s.PopTime(ctx, "foo")
@@ -388,7 +388,7 @@ func TestPopTime(t *testing.T) {
 		t.Errorf("got %v: expected %v", tm, now)
 	}
 
-	_, ok := sd.Values["foo"]
+	_, ok := sd.values["foo"]
 	if ok {
 		t.Errorf("got %v: expected %v", ok, false)
 	}
diff --git a/session.go b/session.go
index c420a2e..6a3f047 100644
--- a/session.go
+++ b/session.go
@@ -34,6 +34,11 @@ type SessionManager struct {
 	// Cookie contains the configuration settings for session cookies.
 	Cookie SessionCookie
 
+	// Codec controls the encoder/decoder used to transform session data to a
+	// byte slice for use by the session store. By default session data is
+	// encoded/decoded using encoding/gob.
+	Codec Codec
+
 	// contextKey is the key used to set and retrieve the session data from a
 	// context.Context. It's automatically generated to ensure uniqueness.
 	contextKey contextKey
@@ -87,6 +92,7 @@ func New() *SessionManager {
 		IdleTimeout: 0,
 		Lifetime:    24 * time.Hour,
 		Store:       memstore.New(),
+		Codec:       gobCodec{},
 		contextKey:  generateContextKey(),
 		Cookie: SessionCookie{
 			Name:     "session",