diff --git a/README.md b/README.md
index 664c0d3..e9daca0 100644
--- a/README.md
+++ b/README.md
@@ -5,4 +5,6 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/imperfectgo/zap-syslog)](https://goreportcard.com/report/github.com/imperfectgo/zap-syslog)
 [![Coverage](https://codecov.io/gh/imperfectgo/zap-syslog/branch/master/graph/badge.svg)](https://codecov.io/gh/imperfectgo/zap-syslog)
 
-Syslog (RFC5424) encoder & syncer for [zap](https://github.com/uber-go/zap).
+Syslog ([RFC5424]) encoder & syncer for [zap](https://github.com/uber-go/zap).
+
+[RFC5424]: https://tools.ietf.org/html/rfc5424
diff --git a/encoder.go b/encoder.go
index 2446706..63a4de8 100644
--- a/encoder.go
+++ b/encoder.go
@@ -46,12 +46,9 @@ const (
 
 var (
 	_ zapcore.Encoder = &syslogEncoder{}
-	_ jsonEncoder     = zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig()).(jsonEncoder)
+	_                 = zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig()).(jsonEncoder)
 )
 
-// Framing configures RFC6587 TCP transport framing.
-type Framing int
-
 // Framing.
 const (
 	NonTransparentFraming Framing = iota
@@ -59,6 +56,9 @@ const (
 	DefaultFraming = NonTransparentFraming
 )
 
+// Framing configures RFC6587 TCP transport framing.
+type Framing int
+
 type jsonEncoder interface {
 	zapcore.Encoder
 	zapcore.ArrayEncoder
@@ -92,7 +92,7 @@ func toRFC5424CompliantASCIIString(s string) string {
 	return strings.Map(rfc5424CompliantASCIIMapper, s)
 }
 
-// NewSyslogEncoder creates a syslogEncoder that you should not use because I'm not done with it yet.
+// NewSyslogEncoder creates a syslogEncoder.
 func NewSyslogEncoder(cfg SyslogEncoderConfig) zapcore.Encoder {
 	if cfg.Hostname == "" {
 		hostname, _ := os.Hostname()
@@ -243,12 +243,12 @@ func (enc *syslogEncoder) EncodeEntry(ent zapcore.Entry, fields []zapcore.Field)
 	msg.AppendInt(version)
 
 	// SP TIMESTAMP
-	ts := ent.Time.UTC().Format(timestampFormat)
-	if ts == "" {
-		ts = nilValue
-	}
 	msg.AppendByte(' ')
-	msg.AppendString(ts)
+	if ent.Time.IsZero() {
+		msg.AppendString(nilValue)
+	} else {
+		msg.AppendString(ent.Time.Format(timestampFormat))
+	}
 
 	// SP HOSTNAME
 	msg.AppendByte(' ')
diff --git a/encoder_test.go b/encoder_test.go
index 9053ac6..dbf215d 100644
--- a/encoder_test.go
+++ b/encoder_test.go
@@ -32,6 +32,7 @@ import (
 
 	"github.com/imperfectgo/zap-syslog/syslog"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"go.uber.org/multierr"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
@@ -66,9 +67,7 @@ func TestToRFC5424CompliantASCIIString(t *testing.T) {
 
 	for _, f := range fixtures {
 		actual := toRFC5424CompliantASCIIString(f.s)
-		if !assert.Equal(t, f.expected, actual) {
-			return
-		}
+		require.Equal(t, f.expected, actual)
 	}
 }
 
@@ -308,17 +307,13 @@ func assertOutput(t testing.TB, desc string, expected string, f func(zapcore.Enc
 	}).(*syslogEncoder)
 	f(enc)
 	buf, err := enc.EncodeEntry(testEntry, nil)
-	if !assert.NoError(t, err) {
-		return
-	}
+	require.NoError(t, err)
 	defer buf.Free()
 
 	const bom = "\xef\xbb\xbf"
 	output := buf.String()
 	i := strings.Index(output, "\xef\xbb\xbf")
-	if !assert.Condition(t, func() (success bool) { return i > 0 }, "not a valid syslog output") {
-		return
-	}
+	require.Condition(t, func() (success bool) { return i > 0 }, "not a valid syslog output")
 
 	jsonString := output[i+len(bom):]
 	assert.Contains(t, jsonString, expected)
@@ -417,7 +412,7 @@ func testSyslogEncoderFraming(t *testing.T, framing Framing) {
 	}
 
 	if !strings.HasPrefix(msg, msgPrefix) {
-		t.Errorf("Wrong syslog output for framing: %s", framing)
+		t.Errorf("Wrong syslog output for framing: %d", framing)
 		t.Log(msg)
 		t.Log(msgPrefix)
 		return
diff --git a/syncer.go b/syncer.go
index 86fe589..df99a87 100644
--- a/syncer.go
+++ b/syncer.go
@@ -30,6 +30,7 @@ var (
 	_ zapcore.WriteSyncer = &ConnSyncer{}
 )
 
+// ConnSyncer describes connection sink for syslog.
 type ConnSyncer struct {
 	network string
 	raddr   string
@@ -83,6 +84,7 @@ func (s *ConnSyncer) Write(p []byte) (n int, err error) {
 	return s.conn.Write(p)
 }
 
+// Sync implements zapcore.WriteSyncer interface.
 func (s *ConnSyncer) Sync() error {
 	return nil
 }
diff --git a/syslog/syslog_test.go b/syslog/syslog_test.go
index 709db33..0eb36b8 100644
--- a/syslog/syslog_test.go
+++ b/syslog/syslog_test.go
@@ -10,7 +10,7 @@ func TestFacilityPriority(t *testing.T) {
 		}
 
 		if actual != priority {
-			t.Fatalf("Expected returned priority: %s, actual: %s", facility, actual)
+			t.Fatalf("Expected returned priority: %d, actual: %d", priority, actual)
 		}
 	}