diff --git a/crates/loro-internal/src/fuzz/recursive_refactored.rs b/crates/loro-internal/src/fuzz/recursive_refactored.rs
index 84c82f40..c80ae97f 100644
--- a/crates/loro-internal/src/fuzz/recursive_refactored.rs
+++ b/crates/loro-internal/src/fuzz/recursive_refactored.rs
@@ -798,6 +798,34 @@ mod failed_tests {
         )
     }
 
+    #[test]
+    fn fuzz_1() {
+        test_multi_sites(
+            5,
+            &mut [
+                List {
+                    site: 3,
+                    container_idx: 30,
+                    key: 0,
+                    value: Null,
+                },
+                SyncAll,
+                Map {
+                    site: 0,
+                    container_idx: 0,
+                    key: 14,
+                    value: Null,
+                },
+                Map {
+                    site: 3,
+                    container_idx: 248,
+                    key: 255,
+                    value: Null,
+                },
+            ],
+        );
+    }
+
     #[test]
     fn notify_causal_order_check() {
         test_multi_sites(
diff --git a/crates/loro-internal/src/refactor/oplog/dag.rs b/crates/loro-internal/src/refactor/oplog/dag.rs
index 4dc0ecdc..85f43479 100644
--- a/crates/loro-internal/src/refactor/oplog/dag.rs
+++ b/crates/loro-internal/src/refactor/oplog/dag.rs
@@ -103,6 +103,7 @@ impl Dag for AppDag {
 }
 
 impl AppDag {
+    // PERF: this may be painfully slow
     /// get the version vector for a certain op.
     /// It's the version when the op is applied
     pub fn get_vv(&self, id: ID) -> Option<ImVersionVector> {
@@ -184,13 +185,13 @@ impl AppDag {
             let id = frontiers[0];
             let Some(rle) = self.map.get(&id.peer) else { unreachable!() };
             let Some(x) = rle.get_by_atom_index(id.counter) else { unreachable!("{} not found", id) };
-            x.element.lamport_end()
+            (id.counter - x.element.cnt) as Lamport + x.element.lamport + 1
         };
 
         for id in frontiers[1..].iter() {
             let Some(rle) = self.map.get(&id.peer) else { unreachable!() };
             let Some(x) = rle.get_by_atom_index(id.counter) else { unreachable!() };
-            lamport = lamport.max(x.element.lamport_end());
+            lamport = lamport.max((id.counter - x.element.cnt) as Lamport + x.element.lamport + 1);
         }
 
         lamport