diff --git a/client.go b/client.go
index 7f5ca3c9..560f8932 100644
--- a/client.go
+++ b/client.go
@@ -111,7 +111,7 @@ func (c *Client) ExchangeRtt(m *Msg, a string) (r *Msg, rtt time.Duration, err e
 	case "tcp", "tcp4", "tcp6":
 		in = make([]byte, MaxMsgSize)
 	case "", "udp", "udp4", "udp6":
-		size := UDPMsgSize
+		size := udpMsgSize
 		for _, r := range m.Extra {
 			if r.Header().Rrtype == TypeOPT {
 				size = int(r.(*RR_OPT).UDPSize())
diff --git a/defaults.go b/defaults.go
index ac4649ce..4bf81bf3 100644
--- a/defaults.go
+++ b/defaults.go
@@ -81,7 +81,7 @@ func (dns *Msg) SetIxfr(z string, serial uint32) *Msg {
 	dns.Question = make([]Question, 1)
 	dns.Ns = make([]RR, 1)
 	s := new(RR_SOA)
-	s.Hdr = RR_Header{z, TypeSOA, ClassINET, DefaultTtl, 0}
+	s.Hdr = RR_Header{z, TypeSOA, ClassINET, defaultTtl, 0}
 	s.Serial = serial
 
 	dns.Question[0] = Question{z, TypeIXFR, ClassINET}
diff --git a/dns.go b/dns.go
index 12e91aec..ba284cf2 100644
--- a/dns.go
+++ b/dns.go
@@ -70,9 +70,9 @@ import (
 const (
 	year68         = 1 << 31 // For RFC1982 (Serial Arithmetic) calculations in 32 bits.
 	DefaultMsgSize = 4096    // Standard default for larger than 512 packets.
-	UDPMsgSize     = 512     // Default buffer size for servers receiving UDP packets.
+	udpMsgSize     = 512     // Default buffer size for servers receiving UDP packets.
 	MaxMsgSize     = 65536   // Largest possible DNS packet.
-	DefaultTtl     = 3600    // Default TTL.
+	defaultTtl     = 3600    // Default TTL.
 )
 
 // Error represents a DNS error
diff --git a/server.go b/server.go
index 62289808..bf242b01 100644
--- a/server.go
+++ b/server.go
@@ -265,7 +265,7 @@ func (srv *Server) ServeUDP(l *net.UDPConn) error {
 		handler = DefaultServeMux
 	}
 	if srv.UDPSize == 0 {
-		srv.UDPSize = UDPMsgSize
+		srv.UDPSize = udpMsgSize
 	}
 	for {
 		m := make([]byte, srv.UDPSize)
diff --git a/zscan.go b/zscan.go
index 466f3ecc..4e3264b6 100644
--- a/zscan.go
+++ b/zscan.go
@@ -170,7 +170,7 @@ func parseZone(r io.Reader, origin, f string, t chan Token, include int) {
 
 	st := _EXPECT_OWNER_DIR // initial state
 	var h RR_Header
-	var defttl uint32 = DefaultTtl
+	var defttl uint32 = defaultTtl
 	var prevName string
 	for l := range c {
 		if _DEBUG {