1 files changed, 7 insertions, 0 deletions
diff --git a/core/blockchain.go b/core/blockchain.go
index 1efd867..4fae221 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -21,6 +21,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"math"
 	"sort"
 	"sync"
 	"time"
@@ -49,6 +50,8 @@ var (
 	ErrMissingRandomness = errors.New("missing block randomness")
 )
 
+const notReadyHeight uint64 = math.MaxUint64
+
 type pendingBlockRecord struct {
 	position types.Position
 	block    *types.Block
@@ -384,6 +387,10 @@ func (bc *blockChain) nextBlock() (uint64, time.Time) {
 	if tip == nil {
 		return types.GenesisHeight, bc.dMoment
 	}
+	if tip != bc.lastDelivered {
+		// If tip is not delivered, we should not proceed to next block.
+		return notReadyHeight, time.Time{}
+	}
 	return tip.Position.Height + 1, tip.Timestamp.Add(config.minBlockInterval)
 }