diff --git a/common/bigendianreader.go b/common/bigendianreader.go
index 3a998db..f4cddc3 100644
--- a/common/bigendianreader.go
+++ b/common/bigendianreader.go
@@ -44,7 +44,7 @@ func (ber *bigEndianReader) u32() (uint32, error) {
 	if ber.err != nil {
 		return 0, ber.err
 	}
-	four := ber.buf[:2]
+	four := ber.buf[:4]
 	_, err := io.ReadFull(ber.parent, four)
 	if err != nil {
 		ber.err = err