diff --git a/mvcc/backend/batch_tx.go b/mvcc/backend/batch_tx.go
index 287f79083e8b..d097dc7f1187 100644
--- a/mvcc/backend/batch_tx.go
+++ b/mvcc/backend/batch_tx.go
@@ -162,9 +162,14 @@ func (t *batchTx) commit(stop bool) {
 		if t.pending == 0 && !stop {
 			t.backend.mu.RLock()
 			defer t.backend.mu.RUnlock()
+			t.tx, err = t.backend.db.Begin(true)
+			if err != nil {
+				plog.Fatalf("cannot begin tx (%s)", err)
+			}
 			atomic.StoreInt64(&t.backend.size, t.tx.Size())
 			return
 		}
+
 		start := time.Now()
 		// gofail: var beforeCommit struct{}
 		err = t.tx.Commit()
diff --git a/mvcc/backend/batch_tx_test.go b/mvcc/backend/batch_tx_test.go
index 582cbf84e7ac..cc120e370858 100644
--- a/mvcc/backend/batch_tx_test.go
+++ b/mvcc/backend/batch_tx_test.go
@@ -195,3 +195,15 @@ func TestBatchTxBatchLimitCommit(t *testing.T) {
 		return nil
 	})
 }
+
+// TestBatchTxCommitSize tests *batchTx.tx.Size call after *batchTx.Commit does not panic.
+// *bolt.Tx commit initializes *bolt.Tx.meta and *bolt.Tx.db as nil. And if *batchTx is not
+// properly initialized, it panics with nil pointer reference.
+func TestBatchTxCommitSize(t *testing.T) {
+	b, tmpPath := NewTmpBackend(time.Hour, 100)
+	defer cleanup(b, tmpPath)
+
+	if _, err := b.Hash(make(map[IgnoreKey]struct{})); err != nil {
+		t.Fatal(err)
+	}
+}