diff --git a/imageproxy.go b/imageproxy.go
index 292285d..4a35925 100644
--- a/imageproxy.go
+++ b/imageproxy.go
@@ -202,7 +202,7 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
 // keys will be copied.
 func copyHeader(dst, src http.Header, keys ...string) {
 	if len(keys) == 0 {
-		for k, _ := range src {
+		for k := range src {
 			keys = append(keys, k)
 		}
 	}
diff --git a/transform.go b/transform.go
index 3428eba..402cbe9 100644
--- a/transform.go
+++ b/transform.go
@@ -105,7 +105,7 @@ func Transform(img []byte, opt Options) ([]byte, error) {
 		}
 	case "tiff":
 		m = transformImage(m, opt)
-		err = tiff.Encode(buf, m, &tiff.Options{tiff.Deflate, true})
+		err = tiff.Encode(buf, m, &tiff.Options{Compression: tiff.Deflate, Predictor: true})
 		if err != nil {
 			return nil, err
 		}