diff --git a/replication.go b/replication.go
index 5586209c..16755f0e 100644
--- a/replication.go
+++ b/replication.go
@@ -22,15 +22,15 @@ func init() {
 
 // Format the given 64bit LSN value into the XXX/XXX format,
 // which is the format reported by postgres.
-func FormatLSN(lsn int64) string {
+func FormatLSN(lsn uint64) string {
 	return fmt.Sprintf("%X/%X", uint32(lsn>>32), uint32(lsn))
 }
 
 // Parse the given XXX/XXX format LSN as reported by postgres,
 // into a 64 bit integer as used internally by the wire procotols
-func ParseLSN(lsn string) (outputLsn int64, err error) {
-	var upperHalf int64
-	var lowerHalf int64
+func ParseLSN(lsn string) (outputLsn uint64, err error) {
+	var upperHalf uint64
+	var lowerHalf uint64
 	var nparsed int
 	nparsed, err = fmt.Sscanf(lsn, "%X/%X", &upperHalf, &lowerHalf)
 	if err != nil {
@@ -50,13 +50,13 @@ func ParseLSN(lsn string) (outputLsn int64, err error) {
 type WalMessage struct {
 	// The WAL start position of this data. This
 	// is the WAL position we need to track.
-	WalStart int64
+	WalStart uint64
 	// The server wal end and server time are
 	// documented to track the end position and current
 	// time of the server, both of which appear to be
 	// unimplemented in pg 9.5.
-	ServerWalEnd int64
-	ServerTime   int64
+	ServerWalEnd uint64
+	ServerTime   uint64
 	// The WAL data is the raw unparsed binary WAL entry.
 	// The contents of this are determined by the output
 	// logical encoding plugin.
@@ -64,10 +64,10 @@ type WalMessage struct {
 }
 
 func (w *WalMessage) Time() time.Time {
-	return time.Unix(0, (w.ServerTime*1000)+epochNano)
+	return time.Unix(0, (int64(w.ServerTime)*1000)+epochNano)
 }
 
-func (w *WalMessage) ByteLag() int64 {
+func (w *WalMessage) ByteLag() uint64 {
 	return (w.ServerWalEnd - w.WalStart)
 }
 
@@ -80,16 +80,16 @@ func (w *WalMessage) String() string {
 type ServerHeartbeat struct {
 	// The current max wal position on the server,
 	// used for lag tracking
-	ServerWalEnd int64
+	ServerWalEnd uint64
 	// The server time, in microseconds since jan 1 2000
-	ServerTime int64
+	ServerTime uint64
 	// If 1, the server is requesting a standby status message
 	// to be sent immediately.
 	ReplyRequested byte
 }
 
 func (s *ServerHeartbeat) Time() time.Time {
-	return time.Unix(0, (s.ServerTime*1000)+epochNano)
+	return time.Unix(0, (int64(s.ServerTime)*1000)+epochNano)
 }
 
 func (s *ServerHeartbeat) String() string {
@@ -109,13 +109,13 @@ type ReplicationMessage struct {
 // all wal positions are typically set to the same value.
 type StandbyStatus struct {
 	// The WAL position that's been locally written
-	WalWritePosition int64
+	WalWritePosition uint64
 	// The WAL position that's been locally flushed
-	WalFlushPosition int64
+	WalFlushPosition uint64
 	// The WAL position that's been locally applied
-	WalApplyPosition int64
+	WalApplyPosition uint64
 	// The client time in microseconds since jan 1 2000
-	ClientTime int64
+	ClientTime uint64
 	// If 1, requests the server to immediately send a
 	// server heartbeat
 	ReplyRequested byte
@@ -123,12 +123,12 @@ type StandbyStatus struct {
 
 // Create a standby status struct, which sets all the WAL positions
 // to the given wal position, and the client time to the current time.
-func NewStandbyStatus(walPosition int64) (status *StandbyStatus) {
+func NewStandbyStatus(walPosition uint64) (status *StandbyStatus) {
 	status = new(StandbyStatus)
 	status.WalFlushPosition = walPosition
 	status.WalApplyPosition = walPosition
 	status.WalWritePosition = walPosition
-	status.ClientTime = (time.Now().UnixNano() - epochNano) / 1000
+	status.ClientTime = uint64((time.Now().UnixNano() - epochNano) / 1000)
 	return
 }
 
@@ -138,10 +138,10 @@ func NewStandbyStatus(walPosition int64) (status *StandbyStatus) {
 func (c *Conn) SendStandbyStatus(k *StandbyStatus) (err error) {
 	writeBuf := newWriteBuf(c, copyData)
 	writeBuf.WriteByte(standbyStatusUpdate)
-	writeBuf.WriteInt64(k.WalWritePosition)
-	writeBuf.WriteInt64(k.WalFlushPosition)
-	writeBuf.WriteInt64(k.WalApplyPosition)
-	writeBuf.WriteInt64(k.ClientTime)
+	writeBuf.WriteInt64(int64(k.WalWritePosition))
+	writeBuf.WriteInt64(int64(k.WalFlushPosition))
+	writeBuf.WriteInt64(int64(k.WalApplyPosition))
+	writeBuf.WriteInt64(int64(k.ClientTime))
 	writeBuf.WriteByte(k.ReplyRequested)
 
 	writeBuf.closeMsg()
@@ -202,9 +202,9 @@ func (c *Conn) readReplicationMessage() (r *ReplicationMessage, err error) {
 			serverWalEnd := reader.readInt64()
 			serverTime := reader.readInt64()
 			walData := reader.readBytes(reader.msgBytesRemaining)
-			walMessage := WalMessage{WalStart: walStart,
-				ServerWalEnd: serverWalEnd,
-				ServerTime:   serverTime,
+			walMessage := WalMessage{WalStart: uint64(walStart),
+				ServerWalEnd: uint64(serverWalEnd),
+				ServerTime:   uint64(serverTime),
 				WalData:      walData,
 			}
 
@@ -213,7 +213,7 @@ func (c *Conn) readReplicationMessage() (r *ReplicationMessage, err error) {
 			serverWalEnd := reader.readInt64()
 			serverTime := reader.readInt64()
 			replyNow := reader.readByte()
-			h := &ServerHeartbeat{ServerWalEnd: serverWalEnd, ServerTime: serverTime, ReplyRequested: replyNow}
+			h := &ServerHeartbeat{ServerWalEnd: uint64(serverWalEnd), ServerTime: uint64(serverTime), ReplyRequested: replyNow}
 			return &ReplicationMessage{ServerHeartbeat: h}, nil
 		}
 	}
diff --git a/replication_test.go b/replication_test.go
index 08affdf1..1d77982a 100644
--- a/replication_test.go
+++ b/replication_test.go
@@ -88,7 +88,7 @@ func TestSimpleReplicationConnection(t *testing.T) {
 	i = 0
 	var foundTimes []int64
 	var foundCount int
-	var maxWal int64
+	var maxWal uint64
 	for {
 		var message *pgx.ReplicationMessage