diff --git a/posting/list.go b/posting/list.go
index 5c841971afa..6b51b18d73e 100644
--- a/posting/list.go
+++ b/posting/list.go
@@ -526,9 +526,12 @@ func (l *List) addMutationInternal(ctx context.Context, txn *Txn, t *pb.Directed
 
 // getMutation returns a marshaled version of posting list mutation stored internally.
 func (l *List) getMutation(startTs uint64) []byte {
-	l.RLock()
-	defer l.RUnlock()
+	l.Lock()
+	defer l.Unlock()
 	if pl, ok := l.mutationMap[startTs]; ok {
+		for _, p := range pl.GetPostings() {
+			p.StartTs = 0
+		}
 		data, err := pl.Marshal()
 		x.Check(err)
 		return data
@@ -596,6 +599,7 @@ func (l *List) pickPostings(readTs uint64) (uint64, []*pb.Posting) {
 					deleteBelowTs = effectiveTs
 					continue
 				}
+				mpost.StartTs = startTs
 				posts = append(posts, mpost)
 			}
 		}