diff --git a/config/options.go b/config/options.go
index 6a340b994cb..3574e974477 100644
--- a/config/options.go
+++ b/config/options.go
@@ -61,7 +61,17 @@ func WithLogger(l log.Logger) Option {
 // to target map[string]interface{} using src.Format codec.
 func defaultDecoder(src *KeyValue, target map[string]interface{}) error {
 	if src.Format == "" {
-		target[src.Key] = src.Value
+		// expand key "aaa.bbb" into map[aaa]map[bbb]interface{}
+		keys := strings.Split(src.Key, ".")
+		for i, k := range keys {
+			if i == len(keys)-1 {
+				target[k] = src.Value
+			} else {
+				sub := make(map[string]interface{})
+				target[k] = sub
+				target = sub
+			}
+		}
 		return nil
 	}
 	if codec := encoding.GetCodec(src.Format); codec != nil {
diff --git a/config/options_test.go b/config/options_test.go
new file mode 100644
index 00000000000..c3769166be0
--- /dev/null
+++ b/config/options_test.go
@@ -0,0 +1,37 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDefaultDecoder(t *testing.T) {
+	src := &KeyValue{
+		Key:    "service",
+		Value:  []byte("config"),
+		Format: "",
+	}
+	target := make(map[string]interface{}, 0)
+	err := defaultDecoder(src, target)
+	assert.Nil(t, err)
+	assert.Equal(t, map[string]interface{}{
+		"service": []byte("config"),
+	}, target)
+
+	src = &KeyValue{
+		Key:    "service.name.alias",
+		Value:  []byte("2233"),
+		Format: "",
+	}
+	target = make(map[string]interface{}, 0)
+	err = defaultDecoder(src, target)
+	assert.Nil(t, err)
+	assert.Equal(t, map[string]interface{}{
+		"service": map[string]interface{}{
+			"name": map[string]interface{}{
+				"alias": []byte("2233"),
+			},
+		},
+	}, target)
+}
diff --git a/config/reader.go b/config/reader.go
index 833508b4033..40e460b3e61 100644
--- a/config/reader.go
+++ b/config/reader.go
@@ -99,6 +99,9 @@ func convertMap(src interface{}) interface{} {
 			dst[k] = convertMap(v)
 		}
 		return dst
+	case []byte:
+		// there will be no binary data in the config data
+		return string(m)
 	default:
 		return src
 	}