diff --git a/extra/time_as_int64_codec.go b/extra/time_as_int64_codec.go
index 202c9ed..f961750 100644
--- a/extra/time_as_int64_codec.go
+++ b/extra/time_as_int64_codec.go
@@ -7,11 +7,12 @@ import (
 )
 
 // keep epoch milliseconds
-func RegisterTimeAsInt64Codec() {
-	jsoniter.RegisterTypeEncoder("time.Time", &timeAsInt64Codec{})
+func RegisterTimeAsInt64Codec(precision time.Duration) {
+	jsoniter.RegisterTypeEncoder("time.Time", &timeAsInt64Codec{precision})
 }
 
 type timeAsInt64Codec struct {
+	precision time.Duration
 }
 
 func (codec *timeAsInt64Codec) IsEmpty(ptr unsafe.Pointer) bool {
@@ -20,7 +21,7 @@ func (codec *timeAsInt64Codec) IsEmpty(ptr unsafe.Pointer) bool {
 }
 func (codec *timeAsInt64Codec) Encode(ptr unsafe.Pointer, stream *jsoniter.Stream) {
 	ts := *((*time.Time)(ptr))
-	stream.WriteInt64(ts.UnixNano())
+	stream.WriteInt64(ts.UnixNano() / codec.precision.Nanoseconds())
 }
 func (codec *timeAsInt64Codec) EncodeInterface(val interface{}, stream *jsoniter.Stream) {
 	jsoniter.WriteToStream(val, stream, codec)
diff --git a/extra/time_as_int64_codec_test.go b/extra/time_as_int64_codec_test.go
index 357685c..7e42a63 100644
--- a/extra/time_as_int64_codec_test.go
+++ b/extra/time_as_int64_codec_test.go
@@ -9,8 +9,16 @@ import (
 
 func Test_time_as_int64(t *testing.T) {
 	should := require.New(t)
-	RegisterTimeAsInt64Codec()
+	RegisterTimeAsInt64Codec(time.Nanosecond)
 	output, err := jsoniter.Marshal(time.Unix(1, 1002))
 	should.Nil(err)
 	should.Equal("1000001002", string(output))
 }
+
+func Test_time_as_int64_keep_microsecond(t *testing.T) {
+	should := require.New(t)
+	RegisterTimeAsInt64Codec(time.Microsecond)
+	output, err := jsoniter.Marshal(time.Unix(1, 1002))
+	should.Nil(err)
+	should.Equal("1000001", string(output))
+}