diff --git a/rtmp/rtmp.go b/rtmp/rtmp.go
index cd5d0fc8..d2a2d124 100644
--- a/rtmp/rtmp.go
+++ b/rtmp/rtmp.go
@@ -215,8 +215,14 @@ var RTMPProtocolStringsLower = [...]string{
 	"rtmfp",
 }
 
+type Session interface {
+	Open() error
+	Write([]byte) (int, error)
+	Close() error
+}
+
 // session provides parameters required for an rtmp communication session.
-type Session struct {
+type session struct {
 	rtmp    *C.RTMP
 	url     string
 	timeout uint
@@ -374,7 +380,7 @@ type C_AMFObject struct {
 
 // NewSession returns a new session.
 func NewSession(url string, connectTimeout uint) Session {
-	return Session{
+	return &session{
 		url:     url,
 		timeout: connectTimeout,
 	}
@@ -382,7 +388,7 @@ func NewSession(url string, connectTimeout uint) Session {
 
 // Open establishes an rtmp connection with the url passed into the
 // constructor
-func (s *Session) Open() error {
+func (s *session) Open() error {
 	if s.rtmp != nil {
 		return errors.New("rtmp: attempt to start already running session")
 	}
@@ -395,7 +401,7 @@ func (s *Session) Open() error {
 }
 
 // Close terminates the rtmp connection
-func (s *Session) Close() error {
+func (s *session) Close() error {
 	if s.rtmp == nil {
 		return Err(3)
 	}
@@ -408,7 +414,7 @@ func (s *Session) Close() error {
 }
 
 // Write writes a frame (flv tag) to the rtmp connection
-func (s *Session) Write(data []byte) (int, error) {
+func (s *session) Write(data []byte) (int, error) {
 	if s.rtmp == nil {
 		return 0, Err(3)
 	}