diff --git a/Thumbnailer.go b/Thumbnailer.go
index ef27601..78dc537 100644
--- a/Thumbnailer.go
+++ b/Thumbnailer.go
@@ -5,6 +5,7 @@ import (
 	"image/jpeg"
 	"image/png"
 	"os"
+	"path/filepath"
 	"strings"
 
 	lru "github.com/hashicorp/golang-lru"
@@ -56,13 +57,10 @@ func (this *Thumbnailer) RenderFile_NoCache(absPath string) ([]byte, error) {
 
 	defer fh.Close()
 
-	if len(absPath) < 4 {
-		return nil, fmt.Errorf("No extension on filename")
-	}
-	extension := strings.ToLower(absPath[len(absPath)-4:])
+	extension := strings.ToLower(filepath.Ext(absPath))
 
 	switch extension {
-	case ".jpg", "jpeg":
+	case "jpg", "jpeg":
 		src, err := jpeg.Decode(fh)
 		if err != nil {
 			return nil, err
@@ -70,7 +68,7 @@ func (this *Thumbnailer) RenderFile_NoCache(absPath string) ([]byte, error) {
 
 		return this.RenderScaledImage(src)
 
-	case ".png":
+	case "png":
 		src, err := png.Decode(fh)
 		if err != nil {
 			return nil, err
@@ -78,11 +76,11 @@ func (this *Thumbnailer) RenderFile_NoCache(absPath string) ([]byte, error) {
 
 		return this.RenderScaledImage(src)
 
-	case ".avi", ".mkv", ".mp4", ".ogm", ".wmv":
+	case "avi", "mkv", "mp4", "ogm", "wmv":
 		return this.RenderScaledFfmpeg(absPath)
 
 	default:
-		return nil, fmt.Errorf("No thumbnailer for file type")
+		return nil, fmt.Errorf("No thumbnailer for file type '%s'", extension)
 
 	}