diff --git a/miner/worker.go b/miner/worker.go
index ded36a9b6..45ff41a9f 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -751,7 +751,9 @@ func (w *worker) resultLoop() {
 				logs = append(logs, receipt.Logs...)
 			}
 			// Commit block and state to database.
+			w.mu.Lock()
 			_, err := w.chain.WriteBlockAndSetHead(block, receipts, logs, task.state, true)
+			w.mu.Unlock()
 			if err != nil {
 				log.Error("Failed writing block to chain", "err", err)
 				continue