diff --git a/entropy.go b/entropy.go
index eec960f..156c1cd 100644
--- a/entropy.go
+++ b/entropy.go
@@ -8,6 +8,7 @@ import (
 	"io"
 )
 
+// Entropy defines a entropy source
 type Entropy interface {
 	Init()
 	Fill(nonce []byte)
diff --git a/kcp_test.go b/kcp_test.go
index 3242be5..d06b061 100644
--- a/kcp_test.go
+++ b/kcp_test.go
@@ -33,7 +33,6 @@ func (p *DelayPacket) ts() int32      { return p._ts }
 func (p *DelayPacket) setts(ts int32) { p._ts = ts }
 
 type DelayTunnel struct{ *list.List }
-type Random *rand.Rand
 type LatencySimulator struct {
 	current                        int32
 	lostrate, rttmin, rttmax, nmax int
diff --git a/sess.go b/sess.go
index 0c541b0..0353404 100644
--- a/sess.go
+++ b/sess.go
@@ -677,12 +677,6 @@ type (
 		rd              atomic.Value     // read deadline for Accept()
 		wd              atomic.Value
 	}
-
-	// a incoming packet definition
-	inPacket struct {
-		from net.Addr
-		data []byte
-	}
 )
 
 // monitor incoming data for all connections of server
diff --git a/sess_test.go b/sess_test.go
index 18e8c4c..5836fe9 100644
--- a/sess_test.go
+++ b/sess_test.go
@@ -19,10 +19,8 @@ const portEcho = "127.0.0.1:9999"
 const portSink = "127.0.0.1:19999"
 const portTinyBufferEcho = "127.0.0.1:29999"
 const portListerner = "127.0.0.1:9998"
-const salt = "kcptest"
 
 var key = []byte("testkey")
-var fec = 4
 var pass = pbkdf2.Key(key, []byte(portSink), 4096, 32, sha1.New)
 
 func init() {