diff --git a/backend_s3.go b/backend_s3.go
index ad71106..4d6c589 100644
--- a/backend_s3.go
+++ b/backend_s3.go
@@ -31,8 +31,12 @@ var (
 func init() {
 	existing_backends = append(existing_backends, "s3")
 
-	s3_endpoint, _ = os.LookupEnv("S3_ENDPOINT")
+	if endpoint, ok := os.LookupEnv("S3_ENDPOINT"); ok {
+		backend = "s3"
+		s3_endpoint = endpoint
+	}
 	if region, ok := os.LookupEnv("S3_REGION"); ok {
+		backend = "s3"
 		s3_region = region
 	}
 	s3_bucket, _ = os.LookupEnv("S3_BUCKET")
diff --git a/main.go b/main.go
index 3515f3d..7203564 100644
--- a/main.go
+++ b/main.go
@@ -11,7 +11,10 @@ import (
 
 var mux = http.NewServeMux()
 
-var ThumbsDir string
+var (
+	ThumbsDir string
+	backend   = "local"
+)
 
 func main() {
 	bind := flag.String("bind", ":8080", "Bind port/socket")
@@ -19,7 +22,7 @@ func main() {
 	publishedImgDir := flag.String("publishedimgdir", "published/", "Directory where save published pictures")
 	nextImgDir := flag.String("nextimgdir", "next/", "Directory where save pictures to review")
 	baseDir := flag.String("basedir", "images/", "Local base directory where find published and next dirs")
-	backend := flag.String("storage-backend", "local", fmt.Sprintf("Storage backend to use (between: %s)", existing_backends))
+	flag.StringVar(&backend, "storage-backend", backend, fmt.Sprintf("Storage backend to use (between: %s)", existing_backends))
 	flag.StringVar(&ThumbsDir, "thumbsdir", "./images/thumbs/", "Directory where generate thumbs")
 	flag.Parse()
 
@@ -56,7 +59,7 @@ func main() {
 	})
 
 	var storage_backend FileBackend
-	if backend == nil || *backend == "local" {
+	if backend == "local" {
 		storage_backend = &LocalFileBackend{*baseDir}
 		if _, err := os.Stat(path.Join(*baseDir, *publishedImgDir)); os.IsNotExist(err) {
 			if err := os.MkdirAll(path.Join(*baseDir, *publishedImgDir), 0755); err != nil {
@@ -68,12 +71,12 @@ func main() {
 				log.Fatal(err)
 			}
 		}
-	} else if *backend == "s3" {
+	} else if backend == "s3" {
 		storage_backend = &S3FileBackend{s3_endpoint, s3_region, s3_bucket, s3_access_key, s3_secret_key, s3_path_style, *baseDir}
 	} else {
-		log.Fatalf("%q is not a valid storage backend.", *backend)
+		log.Fatalf("%q is not a valid storage backend.", backend)
 	}
-	log.Printf("Using %s storage backend", *backend)
+	log.Printf("Using %s storage backend", backend)
 
 	pe := &PictureExplorer{
 		FileBackend:     storage_backend,