diff --git a/algo/common/dispatch.go b/algo/common/dispatch.go
index 2392152..ff42fdf 100644
--- a/algo/common/dispatch.go
+++ b/algo/common/dispatch.go
@@ -1,5 +1,10 @@
 package common
 
+import (
+	"path/filepath"
+	"strings"
+)
+
 type NewDecoderFunc func([]byte) Decoder
 
 var decoderRegistry = make(map[string][]NewDecoderFunc)
@@ -7,6 +12,7 @@ var decoderRegistry = make(map[string][]NewDecoderFunc)
 func RegisterDecoder(ext string, dispatchFunc NewDecoderFunc) {
 	decoderRegistry[ext] = append(decoderRegistry[ext], dispatchFunc)
 }
-func GetDecoder(ext string) []NewDecoderFunc {
+func GetDecoder(filename string) []NewDecoderFunc {
+	ext := strings.ToLower(strings.TrimLeft(filepath.Ext(filename), "."))
 	return decoderRegistry[ext]
 }
diff --git a/algo/common/raw.go b/algo/common/raw.go
index f12e783..3bb8e0b 100644
--- a/algo/common/raw.go
+++ b/algo/common/raw.go
@@ -1,6 +1,9 @@
 package common
 
-import "errors"
+import (
+	"errors"
+	"strings"
+)
 
 type RawDecoder struct {
 	file     []byte
@@ -14,7 +17,7 @@ func NewRawDecoder(file []byte) Decoder {
 func (d *RawDecoder) Validate() error {
 	for ext, sniffer := range snifferRegistry {
 		if sniffer(d.file) {
-			d.audioExt = ext
+			d.audioExt = strings.ToLower(ext)
 			return nil
 		}
 	}
diff --git a/cmd/um/main.go b/cmd/um/main.go
index 6c168b5..4c59a08 100644
--- a/cmd/um/main.go
+++ b/cmd/um/main.go
@@ -76,8 +76,7 @@ func appMain(c *cli.Context) error {
 	if inputStat.IsDir() {
 		return dealDirectory(input, output)
 	} else {
-		ext := strings.TrimLeft(filepath.Ext(inputStat.Name()), ".")
-		allDec := common.GetDecoder(ext)
+		allDec := common.GetDecoder(inputStat.Name())
 		if len(allDec) == 0 {
 			logging.Log().Fatal("skipping while no suitable decoder")
 		}
@@ -94,8 +93,7 @@ func dealDirectory(inputDir string, outputDir string) error {
 		if item.IsDir() {
 			continue
 		}
-		ext := strings.TrimLeft(filepath.Ext(item.Name()), ".")
-		allDec := common.GetDecoder(ext)
+		allDec := common.GetDecoder(item.Name())
 		if len(allDec) == 0 {
 			logging.Log().Info("skipping while no suitable decoder", zap.String("file", item.Name()))
 			continue