diff --git a/benchmark/bench_crypto.cpp b/benchmark/bench_crypto.cpp
index b6d36c237..f915fbcf9 100644
--- a/benchmark/bench_crypto.cpp
+++ b/benchmark/bench_crypto.cpp
@@ -17,10 +17,12 @@
 #include <openssl/evp.h>
 #include <openssl/sha.h>
 
+#include <algorithm>
 #include <array>
 #include <atomic>
 #include <cstdint>
 #include <cstdlib>
+#include <iterator>
 #include <random>
 #include <string>
 #include <vector>
@@ -38,10 +40,7 @@ class SHA1Bench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-      data[i] = 0;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
   }
 
   void run(int n) final {
@@ -64,9 +63,7 @@ class AesEcbBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(key.raw, sizeof(key));
     td::Random::secure_bytes(iv.raw, sizeof(iv));
   }
@@ -95,9 +92,7 @@ class AesIgeEncryptBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(key.raw, sizeof(key));
     td::Random::secure_bytes(iv.raw, sizeof(iv));
   }
@@ -123,9 +118,7 @@ class AesIgeDecryptBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(key.raw, sizeof(key));
     td::Random::secure_bytes(iv.raw, sizeof(iv));
   }
@@ -151,9 +144,7 @@ class AesCtrBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(key.raw, sizeof(key));
     td::Random::secure_bytes(iv.raw, sizeof(iv));
   }
@@ -180,9 +171,7 @@ class AesCtrOpenSSLBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(key.raw, sizeof(key));
     td::Random::secure_bytes(iv.raw, sizeof(iv));
   }
@@ -216,9 +205,7 @@ class AesCbcDecryptBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(as_slice(key));
     td::Random::secure_bytes(as_slice(iv));
   }
@@ -242,9 +229,7 @@ class AesCbcEncryptBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(as_slice(key));
     td::Random::secure_bytes(as_slice(iv));
   }
@@ -269,9 +254,7 @@ class AesIgeShortBench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < SHORT_DATA_SIZE; i++) {
-      data[i] = 123;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
     td::Random::secure_bytes(as_slice(key));
     td::Random::secure_bytes(as_slice(iv));
   }
@@ -372,10 +355,7 @@ class Crc32Bench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-      data[i] = 0;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
   }
 
   void run(int n) final {
@@ -396,10 +376,7 @@ class Crc64Bench final : public td::Benchmark {
   }
 
   void start_up() final {
-    for (int i = 0; i < DATA_SIZE; i++) {
-      data[i] = 123;
-      data[i] = 0;
-    }
+    std::fill(std::begin(data), std::end(data), static_cast<unsigned char>(123));
   }
 
   void run(int n) final {
diff --git a/benchmark/check_tls.cpp b/benchmark/check_tls.cpp
index afc80b800..b2fa2ecd0 100644
--- a/benchmark/check_tls.cpp
+++ b/benchmark/check_tls.cpp
@@ -96,8 +96,8 @@ td::Result<TlsInfo> test_tls(const td::string &url) {
   const size_t MAX_GREASE = 7;
   char greases[MAX_GREASE];
   td::Random::secure_bytes(td::MutableSlice{greases, MAX_GREASE});
-  for (size_t i = 0; i < MAX_GREASE; i++) {
-    greases[i] = static_cast<char>((greases[i] & 0xF0) + 0x0A);
+  for (auto &grease : greases) {
+    grease = static_cast<char>((grease & 0xF0) + 0x0A);
   }
   for (size_t i = 1; i < MAX_GREASE; i += 2) {
     if (greases[i] == greases[i - 1]) {
diff --git a/td/telegram/MessageEntity.cpp b/td/telegram/MessageEntity.cpp
index 0a4203f0c..c091b7ec7 100644
--- a/td/telegram/MessageEntity.cpp
+++ b/td/telegram/MessageEntity.cpp
@@ -2223,8 +2223,8 @@ static FormattedText parse_text_url_entities_v3(Slice text, const vector<Message
     }
 
     size_t splittable_entity_pos[SPLITTABLE_ENTITY_TYPE_COUNT] = {};
-    for (size_t index = 0; index < SPLITTABLE_ENTITY_TYPE_COUNT; index++) {
-      check_non_intersecting(part_splittable_entities[index]);
+    for (const auto &splittable_entities : part_splittable_entities) {
+      check_non_intersecting(splittable_entities);
     }
     if (part_end != max_end) {
       // try to find text_url entities in the left part
diff --git a/td/telegram/StickersManager.cpp b/td/telegram/StickersManager.cpp
index 79921e5bc..56a4758b5 100644
--- a/td/telegram/StickersManager.cpp
+++ b/td/telegram/StickersManager.cpp
@@ -6204,6 +6204,7 @@ void StickersManager::on_update_recent_stickers_limit(int32 recent_stickers_limi
       for (int is_attached = 0; is_attached < 2; is_attached++) {
         if (static_cast<int32>(recent_sticker_ids_[is_attached].size()) > recent_stickers_limit) {
           recent_sticker_ids_[is_attached].resize(recent_stickers_limit);
+          need_update_recent_stickers_[is_attached] = true;
           send_update_recent_stickers();
         }
       }
diff --git a/tdtl/td/tl/tl_simple.h b/tdtl/td/tl/tl_simple.h
index 67ad2a1aa..7647981bf 100644
--- a/tdtl/td/tl/tl_simple.h
+++ b/tdtl/td/tl/tl_simple.h
@@ -23,9 +23,9 @@ namespace tl {
 namespace simple {
 
 inline std::string gen_cpp_name(std::string name) {
-  for (std::size_t i = 0; i < name.size(); i++) {
-    if ((name[i] < '0' || '9' < name[i]) && (name[i] < 'a' || 'z' < name[i]) && (name[i] < 'A' || 'Z' < name[i])) {
-      name[i] = '_';
+  for (auto &c : name) {
+    if ((c < '0' || '9' < c) && (c < 'a' || 'z' < c) && (c < 'A' || 'Z' < c)) {
+      c = '_';
     }
   }
   assert(!name.empty());