diff --git a/dec-decode.go b/dec-decode.go
index 6372dc2..bbfecd9 100644
--- a/dec-decode.go
+++ b/dec-decode.go
@@ -45,7 +45,8 @@ func main() {
 		}
 
 		signature := readSignature(fin)
-		fin.Seek(0, io.SeekStart)
+		_, err = fin.Seek(0, io.SeekStart)
+		errorExit(err)
 		switch signature {
 		case "GCML":
 		case "GCMM":