diff --git a/src/common/command_line.cpp b/src/common/command_line.cpp
index 5f60bef8..925d8ff3 100644
--- a/src/common/command_line.cpp
+++ b/src/common/command_line.cpp
@@ -129,8 +129,8 @@ namespace command_line
   };
   const command_line::arg_descriptor<size_t> arg_block_sync_size  = {
     "block-sync-size"
-  , "How many blocks to sync at once during chain synchronization."
-  , BLOCKS_SYNCHRONIZING_DEFAULT_COUNT
+  , "How many blocks to sync at once during chain synchronization (0 = adaptive)."
+  , 0
   };
   const command_line::arg_descriptor<std::string> arg_check_updates = {
     "check-updates"
diff --git a/src/cryptonote_config.h b/src/cryptonote_config.h
index fd45c082..8ff01cf8 100644
--- a/src/cryptonote_config.h
+++ b/src/cryptonote_config.h
@@ -89,6 +89,7 @@
 
 
 #define BLOCKS_IDS_SYNCHRONIZING_DEFAULT_COUNT          10000  //by default, blocks ids count in synchronizing
+#define BLOCKS_SYNCHRONIZING_DEFAULT_COUNT_PRE_V4       100    //by default, blocks count in blocks downloading
 #define BLOCKS_SYNCHRONIZING_DEFAULT_COUNT              20     //by default, blocks count in blocks downloading
 #define CRYPTONOTE_PROTOCOL_HOP_RELAX_COUNT             3      //value of hop, after which we use only announce of new block
 
diff --git a/src/cryptonote_core/cryptonote_core.cpp b/src/cryptonote_core/cryptonote_core.cpp
index ac2d3023..046b0eca 100644
--- a/src/cryptonote_core/cryptonote_core.cpp
+++ b/src/cryptonote_core/cryptonote_core.cpp
@@ -421,8 +421,6 @@ namespace cryptonote
     CHECK_AND_ASSERT_MES(r, false, "Failed to initialize blockchain storage");
 
     block_sync_size = command_line::get_arg(vm, command_line::arg_block_sync_size);
-    if (block_sync_size == 0)
-      block_sync_size = BLOCKS_SYNCHRONIZING_DEFAULT_COUNT;
 
     MGINFO("Loading checkpoints");
 
@@ -788,6 +786,16 @@ namespace cryptonote
     return true;
   }
   //-----------------------------------------------------------------------------------------------
+  size_t core::get_block_sync_size(uint64_t height) const
+  {
+    static const uint64_t quick_height = m_testnet ? 801219 : 1220516;
+    if (block_sync_size > 0)
+      return block_sync_size;
+    if (height >= quick_height)
+      return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT;
+    return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT_PRE_V4;
+  }
+  //-----------------------------------------------------------------------------------------------
   std::pair<uint64_t, uint64_t> core::get_coinbase_tx_sum(const uint64_t start_offset, const size_t count)
   {
     uint64_t emission_amount = 0;
diff --git a/src/cryptonote_core/cryptonote_core.h b/src/cryptonote_core/cryptonote_core.h
index 63d3cd16..982d6716 100644
--- a/src/cryptonote_core/cryptonote_core.h
+++ b/src/cryptonote_core/cryptonote_core.h
@@ -691,7 +691,7 @@ namespace cryptonote
       *
       * @return the number of blocks to sync in one go
       */
-     size_t get_block_sync_size() const { return block_sync_size; }
+     size_t get_block_sync_size(uint64_t height) const;
 
      /**
       * @brief get the sum of coinbase tx amounts between blocks
diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.inl b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
index c33670a0..60cce459 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler.inl
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
@@ -1286,7 +1286,7 @@ skip:
       NOTIFY_REQUEST_GET_OBJECTS::request req;
       bool is_next = false;
       size_t count = 0;
-      const size_t count_limit = m_core.get_block_sync_size();
+      const size_t count_limit = m_core.get_block_sync_size(m_core.get_current_blockchain_height());
       std::pair<uint64_t, uint64_t> span = std::make_pair(0, 0);
       if (force_next_span)
       {
diff --git a/tests/core_proxy/core_proxy.h b/tests/core_proxy/core_proxy.h
index b7d5725f..6df7e7fc 100644
--- a/tests/core_proxy/core_proxy.h
+++ b/tests/core_proxy/core_proxy.h
@@ -88,7 +88,7 @@ namespace tests
     bool prepare_handle_incoming_blocks(const std::list<cryptonote::block_complete_entry>  &blocks) { return true; }
     bool cleanup_handle_incoming_blocks(bool force_sync = false) { return true; }
     uint64_t get_target_blockchain_height() const { return 1; }
-    size_t get_block_sync_size() const { return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT; }
+    size_t get_block_sync_size(uint64_t height) const { return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT; }
     virtual void on_transaction_relayed(const cryptonote::blobdata& tx) {}
     bool get_testnet() const { return false; }
     bool get_pool_transaction(const crypto::hash& id, cryptonote::blobdata& tx_blob) const { return false; }
diff --git a/tests/unit_tests/ban.cpp b/tests/unit_tests/ban.cpp
index 6fc8b83d..6a1a37fe 100644
--- a/tests/unit_tests/ban.cpp
+++ b/tests/unit_tests/ban.cpp
@@ -65,7 +65,7 @@ public:
   bool prepare_handle_incoming_blocks(const std::list<cryptonote::block_complete_entry>  &blocks) { return true; }
   bool cleanup_handle_incoming_blocks(bool force_sync = false) { return true; }
   uint64_t get_target_blockchain_height() const { return 1; }
-  size_t get_block_sync_size() const { return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT; }
+  size_t get_block_sync_size(uint64_t height) const { return BLOCKS_SYNCHRONIZING_DEFAULT_COUNT; }
   virtual void on_transaction_relayed(const cryptonote::blobdata& tx) {}
   bool get_testnet() const { return false; }
   bool get_pool_transaction(const crypto::hash& id, cryptonote::blobdata& tx_blob) const { return false; }