diff --git a/quorum/types.go b/quorum/types.go
index 44d2d09..18124fb 100644
--- a/quorum/types.go
+++ b/quorum/types.go
@@ -23,7 +23,7 @@ type QbftExtraData struct {
 	Vanity      []byte
 	Validators  []common.Address
 	Vote        *ValidatorVote
-	RoundNumber uint32
+	RoundNumber []byte
 	Seals       [][]byte
 }