diff --git a/src/YesSql.Core/Indexes/IdentityMap.cs b/src/YesSql.Core/Indexes/IdentityMap.cs
index fd216bef..07d85db7 100644
--- a/src/YesSql.Core/Indexes/IdentityMap.cs
+++ b/src/YesSql.Core/Indexes/IdentityMap.cs
@@ -25,8 +25,8 @@ public bool HasEntity(object entity)
 
         public void AddEntity(long id, object entity)
         {
-            _entities.Add(entity, id);
-            _documentIds.Add(id, entity);
+            _entities.TryAdd(entity, id);
+            _documentIds.TryAdd(id, entity);
         }
 
         public void AddDocument(Document doc)