diff --git a/cmd/cdr/main.go b/cmd/cdr/main.go
index d9de0e6..a6cbd99 100644
--- a/cmd/cdr/main.go
+++ b/cmd/cdr/main.go
@@ -3,7 +3,10 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
 	"os"
+	"path/filepath"
+	"strings"
 
 	"github.com/thebaer/cdr"
 )
@@ -16,13 +19,19 @@ var printUsage = func() {
 func main() {
 	flag.Usage = printUsage
 	flag.Parse()
-	if flag.NArg() != 1 {
-		printUsage()
-		return
-	}
 
-	file := flag.Arg(0)
-	oldFilename, trackName := cdr.RenameTrack(file)
-	fmt.Println("Renaming", oldFilename, "to", trackName)
-	os.Rename(oldFilename, trackName)
+	wd, err := os.Getwd()
+	if err != nil {
+		log.Fatal(err)
+	}
+	filepath.Walk(wd, func(path string, i os.FileInfo, err error) error {
+		if !i.IsDir() && !strings.HasPrefix(i.Name(), ".") {
+			fName := i.Name()
+			trackName := cdr.RenameTrack(fName)
+			fmt.Println("Renaming", fName, "to", trackName)
+			os.Rename(fName, trackName)
+		}
+
+		return nil
+	})
 }
diff --git a/sanitize.go b/sanitize.go
index 15284ba..a7be5bb 100644
--- a/sanitize.go
+++ b/sanitize.go
@@ -15,26 +15,27 @@ var trackNameReg = regexp.MustCompile("^([0-9]{2}).+")
 
 // RenameTrack takes a filename, opens it, reads the metadata, and returns both
 // the old and new filename.
-func RenameTrack(file string) (string, string) {
+func RenameTrack(file string) string {
 	f, err := os.Open(file)
 	if err != nil {
 		fmt.Printf("error loading file: %v", err)
-		return "", ""
+		return ""
 	}
 	defer f.Close()
 
-	fMatch := trackNameReg.FindStringSubmatch(f.Name())
+	fName := f.Name()
+	fMatch := trackNameReg.FindStringSubmatch(fName)
 	if len(fMatch) < 2 {
 		log.Fatal("Unexpect filename format")
 	}
 	trackNum := fMatch[1]
-	ext := ".mp3"
+	ext := fName[strings.LastIndex(fName, "."):]
 
 	m, err := tag.ReadFrom(f)
 	if err != nil {
 		log.Fatal(err)
 	}
-	return f.Name(), fmt.Sprintf("%s-%s-%s%s", trackNum, Sanitize(m.Artist()), Sanitize(m.Title()), ext)
+	return fmt.Sprintf("%s-%s-%s%s", trackNum, Sanitize(m.Artist()), Sanitize(m.Title()), ext)
 }
 
 // Sanitize takes a string and removes problematic characters from it.