diff --git a/tdutils/td/utils/FlatHashMap.h b/tdutils/td/utils/FlatHashMap.h
index c1bd4ef47..097d02939 100644
--- a/tdutils/td/utils/FlatHashMap.h
+++ b/tdutils/td/utils/FlatHashMap.h
@@ -14,13 +14,13 @@
 
 namespace td {
 template <class KeyT, class ValueT, class HashT = std::hash<KeyT>, class EqT = std::equal_to<KeyT>>
-using FlatHashMap = FlatHashMapImpl<KeyT, ValueT, HashT, EqT>;
-//using FlatHashMap = FlatHashMapChunks<KeyT, ValueT, HashT, EqT>;
+//using FlatHashMap = FlatHashMapImpl<KeyT, ValueT, HashT, EqT>;
+using FlatHashMap = FlatHashMapChunks<KeyT, ValueT, HashT, EqT>;
 //using FlatHashMap = std::unordered_map<KeyT, ValueT, HashT, EqT>;
 
 template <class KeyT, class HashT = std::hash<KeyT>, class EqT = std::equal_to<KeyT>>
-using FlatHashSet = FlatHashSetImpl<KeyT, HashT, EqT>;
-//using FlatHashSet = FlatHashSetChunks<KeyT, HashT, EqT>;
+//using FlatHashSet = FlatHashSetImpl<KeyT, HashT, EqT>;
+using FlatHashSet = FlatHashSetChunks<KeyT, HashT, EqT>;
 //using FlatHashSet = std::unordered_set<KeyT, HashT, EqT>;
 
 }  // namespace td
diff --git a/tdutils/td/utils/FlatHashMapChunks.h b/tdutils/td/utils/FlatHashMapChunks.h
index 765521b65..aaa9f532c 100644
--- a/tdutils/td/utils/FlatHashMapChunks.h
+++ b/tdutils/td/utils/FlatHashMapChunks.h
@@ -6,7 +6,6 @@
 //
 #pragma once
 
-#include "td/utils/algorithm.h"
 #include "td/utils/bits.h"
 #include "td/utils/common.h"
 #include "td/utils/FlatHashMapLinear.h"
@@ -224,9 +223,9 @@ class FlatHashTableChunks {
 
   FlatHashTableChunks(std::initializer_list<Node> nodes) {
     reserve(nodes.size());
-    for (auto &node : reversed(nodes)) {
+    for (auto &node : nodes) {
       CHECK(!node.empty());
-      if (count(node.first) > 0) {
+      if (count(node.key()) > 0) {
         continue;
       }
       emplace_node(Node{node.first, node.second});
diff --git a/tdutils/td/utils/FlatHashMapLinear.h b/tdutils/td/utils/FlatHashMapLinear.h
index 4dcd6788b..d9b3ebb15 100644
--- a/tdutils/td/utils/FlatHashMapLinear.h
+++ b/tdutils/td/utils/FlatHashMapLinear.h
@@ -276,8 +276,6 @@ class FlatHashTable {
           break;
         }
         if (EqT()(node.key(), new_node.key())) {
-          node.clear();
-          node.copy_from(new_node);
           break;
         }
         next_bucket(bucket);
diff --git a/tdutils/td/utils/algorithm.h b/tdutils/td/utils/algorithm.h
index 32c94fdb6..0c3702d8c 100644
--- a/tdutils/td/utils/algorithm.h
+++ b/tdutils/td/utils/algorithm.h
@@ -181,14 +181,12 @@ struct reversion_wrapper {
 
 template <typename T>
 auto begin(reversion_wrapper<T> w) {
-  using std::rbegin;
-  return rbegin(w.iterable);
+  return w.iterable.rbegin();
 }
 
 template <typename T>
 auto end(reversion_wrapper<T> w) {
-  using std::rend;
-  return rend(w.iterable);
+  return w.iterable.rend();
 }
 }  // namespace detail
 
diff --git a/tdutils/test/HashSet.cpp b/tdutils/test/HashSet.cpp
index 949918bb4..0d4fa7bea 100644
--- a/tdutils/test/HashSet.cpp
+++ b/tdutils/test/HashSet.cpp
@@ -119,7 +119,7 @@ TEST(FlatHashMap, basic) {
 
   {
     td::FlatHashMap<int, td::string> map = {{1, "hello"}, {1, "world"}};
-    ASSERT_EQ("world", map[1]);
+    ASSERT_EQ("hello", map[1]);
     ASSERT_EQ(1u, map.size());
   }