diff --git a/packet.go b/packet.go
index d3d830f..d58edec 100644
--- a/packet.go
+++ b/packet.go
@@ -245,7 +245,7 @@ func ParseSessionData(session *Session, encrypted []byte) ([]byte, error) {
 
 func NewSessionClose(session *Session) []byte {
   packet := make([]byte, COMMAND_LENGTH + ID_LENGTH + SESSION_CLOSE_LENGTH)
-  packet[0] = COMMAND_LENGTH
+  packet[0] = byte(SESSION_CLOSE)
   copy(packet[1:], session.ID[:])
 
   hmac := sha512.Sum512(append(session.ID[:], session.secret...))
diff --git a/packet_test.go b/packet_test.go
index d37b979..6bd91ad 100644
--- a/packet_test.go
+++ b/packet_test.go
@@ -25,6 +25,9 @@ func TestSessionOpen(t *testing.T) {
 
   client_so, client_ecdh, err := NewSessionOpen(client_key)
   fatalErr(t, err)
+  if client_so[0] != byte(SESSION_OPEN) {
+    t.Fatalf("Session open command byte mismatch(%x != %x)", client_so[0], SESSION_OPEN)
+  }
 
   server_so, server_ecdh, err := NewSessionOpen(server_key)
   fatalErr(t, err)
@@ -71,7 +74,14 @@ func TestSessionConnect(t *testing.T) {
   test_addr, err := net.ResolveUDPAddr("udp", "127.0.0.1:8080")
   fatalErr(t, err)
 
+  session_id := ID[SessionID](secret)
   session_connect := NewSessionConnect(test_addr, secret)
+  if session_connect[0] != byte(SESSION_CONNECT) {
+    t.Fatalf("Session open command byte mismatch(%x != %x)", session_connect[0], SESSION_CONNECT)
+  } else if slices.Compare(session_connect[COMMAND_LENGTH:COMMAND_LENGTH+ID_LENGTH], session_id[:]) != 0 {
+    t.Fatal("Session open ID mismatch")
+  }
+
   parsed_addr, err := ParseSessionConnect(session_connect[COMMAND_LENGTH + ID_LENGTH:], secret)
   fatalErr(t, err)
 
@@ -100,10 +110,16 @@ func TestSessionData(t *testing.T) {
   fatalErr(t, err)
 
   message := []byte("hello")
-  server_hello, err := NewSessionData(&server_session, message)
+  session_data, err := NewSessionData(&server_session, message)
   fatalErr(t, err)
 
-  parsed_message, err := ParseSessionData(&client_session, server_hello[COMMAND_LENGTH+ID_LENGTH:])
+  if session_data[0] != byte(SESSION_DATA) {
+    t.Fatalf("Session data command byte mismatch(%x != %x)", session_data[0], SESSION_DATA)
+  } else if slices.Compare(session_data[COMMAND_LENGTH:COMMAND_LENGTH+ID_LENGTH], server_session.ID[:]) != 0 {
+    t.Fatal("Session data ID mismatch")
+  }
+
+  parsed_message, err := ParseSessionData(&client_session, session_data[COMMAND_LENGTH+ID_LENGTH:])
   fatalErr(t, err)
 
   if slices.Compare(message, parsed_message) != 0 {
@@ -131,5 +147,12 @@ func TestSessionClose(t *testing.T) {
   fatalErr(t, err)
 
   session_close := NewSessionClose(&client_session)
+
+  if session_close[0] != byte(SESSION_CLOSE) {
+    t.Fatalf("Session close command byte mismatch(%x != %x)", session_close[0], SESSION_CLOSE)
+  } else if slices.Compare(session_close[COMMAND_LENGTH:COMMAND_LENGTH+ID_LENGTH], server_session.ID[:]) != 0 {
+    t.Fatal("Session close ID mismatch")
+  }
+
   fatalErr(t, ParseSessionClose(&server_session, session_close[COMMAND_LENGTH+ID_LENGTH:]))
 }