diff --git a/repo/blob/gcs/gcs_storage.go b/repo/blob/gcs/gcs_storage.go
index b0fc0fb02..600eebebc 100644
--- a/repo/blob/gcs/gcs_storage.go
+++ b/repo/blob/gcs/gcs_storage.go
@@ -267,6 +267,11 @@ func New(ctx context.Context, opt *Options) (blob.Storage, error) {
 		return nil, errors.New("bucket name must be specified")
 	}
 
+	// make sure the bucket exists
+	if _, err := cli.Bucket(opt.BucketName).Attrs(ctx); err != nil {
+		return nil, errors.Wrap(err, "unable to read bucket")
+	}
+
 	return &gcsStorage{
 		Options:           *opt,
 		ctx:               ctx,
diff --git a/repo/blob/s3/s3_storage.go b/repo/blob/s3/s3_storage.go
index f9194680a..27261e7a6 100644
--- a/repo/blob/s3/s3_storage.go
+++ b/repo/blob/s3/s3_storage.go
@@ -233,6 +233,15 @@ func New(ctx context.Context, opt *Options) (blob.Storage, error) {
 	downloadThrottler := iothrottler.NewIOThrottlerPool(toBandwidth(opt.MaxDownloadSpeedBytesPerSecond))
 	uploadThrottler := iothrottler.NewIOThrottlerPool(toBandwidth(opt.MaxUploadSpeedBytesPerSecond))
 
+	ok, err := cli.BucketExistsWithContext(ctx, opt.BucketName)
+	if err != nil {
+		return nil, errors.Wrapf(err, "unable to determine if bucket %q exists", opt.BucketName)
+	}
+
+	if !ok {
+		return nil, errors.Errorf("bucket %q does not exist", opt.BucketName)
+	}
+
 	return &s3Storage{
 		Options:           *opt,
 		ctx:               ctx,