diff --git a/td/telegram/files/FileManager.cpp b/td/telegram/files/FileManager.cpp
index 4410bce1..10a7f3c5 100644
--- a/td/telegram/files/FileManager.cpp
+++ b/td/telegram/files/FileManager.cpp
@@ -3833,39 +3833,60 @@ void FileManager::memory_cleanup() {
     }
 
     /* DESTROY INVALID file_hash_to_file_id_ */
-    for (const auto &pair : file_hash_to_file_id_) {
-      auto &file = file_id_info_[pair.second.fast_get()];
-      if (&file == nullptr || file_nodes_[file.node_id_] == nullptr) {
-        file_hash_to_file_id_.erase(pair.first);
+    {
+      auto it = file_hash_to_file_id_.begin();
+      while (it != file_hash_to_file_id_.end()) {
+        auto &file = file_id_info_[it->second.fast_get()];
+        if (file_nodes_[file.node_id_] == nullptr) {
+          file_hash_to_file_id_.erase(it);
+        } else {
+          it++;
+        }
       }
     }
 
     /* DESTROY INVALID local_location_to_file_id_ */
-    for (const auto &pair : local_location_to_file_id_) {
-      auto &file = file_id_info_[pair.second.fast_get()];
-      if (&file == nullptr || file_nodes_[file.node_id_] == nullptr) {
-        local_location_to_file_id_.erase(pair.first);
+    {
+      auto it = local_location_to_file_id_.begin();
+      while (it != local_location_to_file_id_.end()) {
+        auto &file = file_id_info_[it->second.fast_get()];
+        if (file_nodes_[file.node_id_] == nullptr) {
+          it = local_location_to_file_id_.erase(it);
+        } else {
+          it++;
+        }
       }
     }
 
     /* DESTROY INVALID generate_location_to_file_id_ */
-    for (const auto &pair : generate_location_to_file_id_) {
-      auto &file = file_id_info_[pair.second.fast_get()];
-      if (&file == nullptr || file_nodes_[file.node_id_] == nullptr) {
-        generate_location_to_file_id_.erase(pair.first);
+    {
+      auto it = generate_location_to_file_id_.begin();
+      while (it != generate_location_to_file_id_.end()) {
+        auto &file = file_id_info_[it->second.fast_get()];
+        if (file_nodes_[file.node_id_] == nullptr) {
+          it = generate_location_to_file_id_.erase(it);
+        } else {
+          it++;
+        }
       }
     }
 
     /* DESTROY INVALID remote_location_info_ */
-    for (const auto &pair : remote_location_info_.get_map()) {
-      auto &file = file_id_info_[pair.first.file_id_.fast_get()];
-      if (&file == nullptr || file_nodes_[file.node_id_] == nullptr) {
-        remote_location_info_.erase_map_key(pair.first, pair.second);
+    {
+      auto map = remote_location_info_.get_map();
+      auto it = map.begin();
+      while (it != map.end()) {
+        auto &file = file_id_info_[it->first.file_id_.fast_get()];
+        if (file_nodes_[file.node_id_] == nullptr) {
+          map.erase(it);
+          remote_location_info_.erase(it->second);
+        } else {
+          it++;
+        }
       }
     }
 
     file_hash_to_file_id_.rehash(0);
-
     file_id_info_.shrink_to_fit();
     empty_file_ids_.shrink_to_fit();
     empty_node_ids_.shrink_to_fit();
diff --git a/tdutils/td/utils/Enumerator.h b/tdutils/td/utils/Enumerator.h
index b22107e7..3cc1f4af 100644
--- a/tdutils/td/utils/Enumerator.h
+++ b/tdutils/td/utils/Enumerator.h
@@ -19,8 +19,8 @@ class Enumerator {
  public:
   using Key = int32;
 
-  std::map<ValueT, int32> get_map() const {
-    return map_;
+  std::map<ValueT, int32> &get_map() const {
+    return *map_;
   }
 
   std::pair<Key, bool> next() {
@@ -33,10 +33,9 @@ class Enumerator {
     return std::make_pair((Key) (arr_.size() + 1), false);
   }
 
-  void erase_map_key(ValueT key_x, Key key_y) {
+  void erase(Key key_y) {
     auto pos_y = static_cast<Key>(key_y - 1);
     empty_id_.push_back(key_y);
-    map_.erase(key_x);
     arr_[pos_y] = nullptr;
   }