diff --git a/reflect_map.go b/reflect_map.go
index 58296713..4e479c8a 100644
--- a/reflect_map.go
+++ b/reflect_map.go
@@ -2,11 +2,12 @@ package jsoniter
 
 import (
 	"fmt"
-	"github.com/modern-go/reflect2"
 	"io"
 	"reflect"
 	"sort"
 	"unsafe"
+
+	"github.com/modern-go/reflect2"
 )
 
 func decoderOfMap(ctx *ctx, typ reflect2.Type) ValDecoder {
@@ -106,15 +107,17 @@ func encoderOfMapKey(ctx *ctx, typ reflect2.Type) ValEncoder {
 		}
 	}
 
-	if typ == textMarshalerType {
-		return &directTextMarshalerEncoder{
-			stringEncoder: ctx.EncoderOf(reflect2.TypeOf("")),
+	if typ.Kind() != reflect.String {
+		if typ == textMarshalerType {
+			return &directTextMarshalerEncoder{
+				stringEncoder: ctx.EncoderOf(reflect2.TypeOf("")),
+			}
 		}
-	}
-	if typ.Implements(textMarshalerType) {
-		return &textMarshalerEncoder{
-			valType:       typ,
-			stringEncoder: ctx.EncoderOf(reflect2.TypeOf("")),
+		if typ.Implements(textMarshalerType) {
+			return &textMarshalerEncoder{
+				valType:       typ,
+				stringEncoder: ctx.EncoderOf(reflect2.TypeOf("")),
+			}
 		}
 	}
 
diff --git a/stream_float.go b/stream_float.go
index 826aa594..eddd831b 100644
--- a/stream_float.go
+++ b/stream_float.go
@@ -27,6 +27,14 @@ func (stream *Stream) WriteFloat32(val float32) {
 		}
 	}
 	stream.buf = strconv.AppendFloat(stream.buf, float64(val), fmt, -1, 32)
+	if fmt == 'e' {
+		// clean up e-09 to e-9
+		n := len(stream.buf)
+		if n >= 4 && stream.buf[n-4] == 'e' && stream.buf[n-3] == '-' && stream.buf[n-2] == '0' {
+			stream.buf[n-2] = stream.buf[n-1]
+			stream.buf = stream.buf[:n-1]
+		}
+	}
 }
 
 // WriteFloat32Lossy write float32 to stream with ONLY 6 digits precision although much much faster
@@ -76,6 +84,14 @@ func (stream *Stream) WriteFloat64(val float64) {
 		}
 	}
 	stream.buf = strconv.AppendFloat(stream.buf, float64(val), fmt, -1, 64)
+	if fmt == 'e' {
+		// clean up e-09 to e-9
+		n := len(stream.buf)
+		if n >= 4 && stream.buf[n-4] == 'e' && stream.buf[n-3] == '-' && stream.buf[n-2] == '0' {
+			stream.buf[n-2] = stream.buf[n-1]
+			stream.buf = stream.buf[:n-1]
+		}
+	}
 }
 
 // WriteFloat64Lossy write float64 to stream with ONLY 6 digits precision although much much faster
diff --git a/value_tests/float_test.go b/value_tests/float_test.go
index 3c00b269..1f2c0075 100644
--- a/value_tests/float_test.go
+++ b/value_tests/float_test.go
@@ -4,10 +4,11 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"github.com/json-iterator/go"
-	"github.com/stretchr/testify/require"
 	"strconv"
 	"testing"
+
+	jsoniter "github.com/json-iterator/go"
+	"github.com/stretchr/testify/require"
 )
 
 func Test_read_float(t *testing.T) {
@@ -88,7 +89,7 @@ func Test_write_float32(t *testing.T) {
 
 	stream = jsoniter.NewStream(jsoniter.ConfigDefault, nil, 0)
 	stream.WriteFloat32(float32(0.0000001))
-	should.Equal("1e-07", string(stream.Buffer()))
+	should.Equal("1e-7", string(stream.Buffer()))
 }
 
 func Test_write_float64(t *testing.T) {
@@ -125,5 +126,5 @@ func Test_write_float64(t *testing.T) {
 
 	stream = jsoniter.NewStream(jsoniter.ConfigDefault, nil, 0)
 	stream.WriteFloat64(float64(0.0000001))
-	should.Equal("1e-07", string(stream.Buffer()))
+	should.Equal("1e-7", string(stream.Buffer()))
 }