diff --git a/src/cryptonote_basic/difficulty.cpp b/src/cryptonote_basic/difficulty.cpp
index d51653e89..dc7396ac1 100644
--- a/src/cryptonote_basic/difficulty.cpp
+++ b/src/cryptonote_basic/difficulty.cpp
@@ -214,6 +214,7 @@ namespace cryptonote {
       return 1;
     }
     if (HEIGHT < 200 && HEIGHT > 2 && m_nettype == TESTNET) { return 500; }
+    if (HEIGHT <= DIFFICULTY_RESET_HEIGHT + DIFFICULTY_WINDOW && HEIGHT >= DIFFICULTY_RESET_HEIGHT && m_nettype == MAINNET) { return DIFFICULTY_RESET_LEVEL; }
     static_assert(DIFFICULTY_WINDOW >= 2, "Window is too small");
     assert(length <= DIFFICULTY_WINDOW);
     sort(timestamps.begin(), timestamps.end());
diff --git a/src/cryptonote_config.h b/src/cryptonote_config.h
index 7d7fb84c6..245f7a959 100644
--- a/src/cryptonote_config.h
+++ b/src/cryptonote_config.h
@@ -87,6 +87,8 @@
 #define DIFFICULTY_BLOCKS_COUNT_V3                      DIFFICULTY_WINDOW_V3 + 1 // added +1 to make N=N
 #define DIFFICULTY_BLOCKS_COUNT_V2                      DIFFICULTY_WINDOW_V2 + 1 // added +1 to make N=N
 #define DIFFICULTY_BLOCKS_COUNT                         DIFFICULTY_WINDOW + DIFFICULTY_LAG
+#define DIFFICULTY_RESET_HEIGHT                         331519 // ~July 4, 2021 Pool Independence Day
+#define DIFFICULTY_RESET_LEVEL                          100000000 // 100 mill
 
 #define CRYPTONOTE_LOCKED_TX_ALLOWED_DELTA_SECONDS_V1   DIFFICULTY_TARGET_V1 * CRYPTONOTE_LOCKED_TX_ALLOWED_DELTA_BLOCKS
 #define CRYPTONOTE_LOCKED_TX_ALLOWED_DELTA_SECONDS_V2   DIFFICULTY_TARGET_V2 * CRYPTONOTE_LOCKED_TX_ALLOWED_DELTA_BLOCKS
diff --git a/src/cryptonote_core/blockchain.cpp b/src/cryptonote_core/blockchain.cpp
index e067f2dde..91c4f58d5 100644
--- a/src/cryptonote_core/blockchain.cpp
+++ b/src/cryptonote_core/blockchain.cpp
@@ -948,7 +948,7 @@ start:
 
   difficulty_type diff = next_difficulty(timestamps, m_nettype, difficulties, target, HEIGHT);
 
-  if (version >= 11) {
+  if (version <= 17 && version >= 11) {
     diff = next_difficulty_v5(timestamps, m_nettype, difficulties, T, N, HEIGHT);
   } else if (version == 10) {
     diff = next_difficulty_v4(timestamps, m_nettype, difficulties, HEIGHT);
@@ -1043,7 +1043,7 @@ size_t Blockchain::recalculate_difficulties(boost::optional<uint64_t> start_heig
     size_t target = get_ideal_hard_fork_version(height) < 2 ? DIFFICULTY_TARGET_V1 : DIFFICULTY_TARGET_V2;
     difficulty_type recalculated_diff = next_difficulty(timestamps, m_nettype, difficulties, target, HEIGHT);
     
-    if (version >= 11) {
+    if (version <= 17 && version >= 11) {
       recalculated_diff = next_difficulty_v5(timestamps, m_nettype, difficulties, T, N, HEIGHT);
     } else if (version == 10) {
       recalculated_diff = next_difficulty_v4(timestamps, m_nettype, difficulties, HEIGHT);
@@ -1357,7 +1357,7 @@ difficulty_type Blockchain::get_next_difficulty_for_alternative_chain(const std:
   uint64_t HEIGHT = m_db->height();
 
   // calculate the difficulty target for the block and return it
-  if (version >= 11) {
+  if (version <= 17 && version >= 11) {
     return next_difficulty_v5(timestamps, m_nettype, cumulative_difficulties, T, N, HEIGHT);
   } else if (version == 10) {
     return next_difficulty_v4(timestamps, m_nettype, cumulative_difficulties, HEIGHT);
diff --git a/src/hardforks/hardforks.cpp b/src/hardforks/hardforks.cpp
index 3554bde2e..59cf8c4a5 100644
--- a/src/hardforks/hardforks.cpp
+++ b/src/hardforks/hardforks.cpp
@@ -43,6 +43,7 @@ const hardfork_t mainnet_hard_forks[] = {
   { 15, 160777, 0, 1573280497 },
   { 16, 253999, 0, 1600576508 },
   { 17, 254287, 0, 1600576524 },
+  { 18, 331519, 0, 1623245591 },
 };
 const size_t num_mainnet_hard_forks = sizeof(mainnet_hard_forks) / sizeof(mainnet_hard_forks[0]);