diff --git a/edns.go b/edns.go
index c9181783de..bcc3c6778d 100644
--- a/edns.go
+++ b/edns.go
@@ -575,33 +575,36 @@ func (e *EDNS0_N3U) copy() EDNS0 { return &EDNS0_N3U{e.Code, e.AlgCode} }
 
 // EDNS0_EXPIRE implements the EDNS0 option as described in RFC 7314.
 type EDNS0_EXPIRE struct {
-	Code   uint16 // Always EDNS0EXPIRE
-	Expire uint32
+	Code   uint16  // Always EDNS0EXPIRE
+	Expire []uint8 // can be zero or 4 length
 }
 
 // Option implements the EDNS0 interface.
 func (e *EDNS0_EXPIRE) Option() uint16 { return EDNS0EXPIRE }
-func (e *EDNS0_EXPIRE) String() string { return strconv.FormatUint(uint64(e.Expire), 10) }
 func (e *EDNS0_EXPIRE) copy() EDNS0    { return &EDNS0_EXPIRE{e.Code, e.Expire} }
-
 func (e *EDNS0_EXPIRE) pack() ([]byte, error) {
-	b := make([]byte, 4)
-	binary.BigEndian.PutUint32(b, e.Expire)
-	return b, nil
+	if len(e.Expire) != 0 && len(e.Expire) != 4 {
+		return nil, errors.New("dns: expire length is not 0/4")
+	}
+	return e.Expire, nil
 }
-
 func (e *EDNS0_EXPIRE) unpack(b []byte) error {
-	if len(b) == 0 {
-		// zero-length EXPIRE query, see RFC 7314 Section 2
-		return nil
+	if len(b) != 0 || len(b) != 4 {
+		return errors.New("dns: expire length mismatch, want 0/4 but got " + strconv.Itoa(len(b)))
 	}
-	if len(b) < 4 {
-		return ErrBuf
-	}
-	e.Expire = binary.BigEndian.Uint32(b)
+	e.Expire = b
 	return nil
 }
 
+func (e *EDNS0_EXPIRE) String() (s string) {
+	if len(e.Expire) == 0 {
+		s = "<omitted>"
+	} else {
+		s = fmt.Sprintf("<%d>", binary.BigEndian.Uint32(e.Expire))
+	}
+	return s
+}
+
 // The EDNS0_LOCAL option is used for local/experimental purposes. The option
 // code is recommended to be within the range [EDNS0LOCALSTART, EDNS0LOCALEND]
 // (RFC6891), although any unassigned code can actually be used.  The content of