diff --git a/nori.go b/nori.go
index 9c7dbb0..f6830c1 100644
--- a/nori.go
+++ b/nori.go
@@ -20,7 +20,7 @@ type Nori struct {
 	lastSignature [4]byte
 }
 
-func (n *Nori) Decode(r io.Reader) error {
+func (n *Nori) Decode(r io.ReadSeeker) error {
 	rd := reflectReader(r)
 	n.Gawi = &GawiSection{}
 	if _, err := io.ReadFull(rd, n.lastSignature[:]); err != nil {