diff --git a/storage/s3.go b/storage/s3.go
index 934b9c1..1dc5dcf 100644
--- a/storage/s3.go
+++ b/storage/s3.go
@@ -66,8 +66,10 @@ func NewS3Client(cfg Cfg) (*S3Client, error) {
 		awsCfg.EndpointResolverWithOptions = resolver
 	}
 
-	if !cfg.UseIAM {
+	if !cfg.UseIAM && len(cfg.AK) != 0 && len(cfg.SK) != 0 {
 		awsCfg.Credentials = credentials.NewStaticCredentialsProvider(cfg.AK, cfg.SK, "")
+	} else {
+		awsCfg.Credentials = aws.AnonymousCredentials{}
 	}
 	return &S3Client{cli: s3.NewFromConfig(awsCfg)}, nil
 }