diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index 5ac953dd..c97e428d 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -855,6 +855,37 @@ class Chain extends AsyncEmitter {
 
     assert(fork, 'No free space or data corruption.');
 
+    // Check NLR (No Large Reorganization)
+    if  (tip.height - fork.height >= this.nlrLimit) {
+      if (this.nlrLimit !== 0) {
+        this.logger.warning(
+          'NLR Activated: current=%h(%d) fork=%h(%d) reorg_size=%d',
+          tip.hash,
+          tip.height,
+          competitor.hash,
+          competitor.height,
+          tip.height - fork.height
+        );
+
+        const entryWithMostWork = (tip.height > competitor.height) ? tip : competitor
+
+        // mark invalid_child from tip of fork to second block of fork
+        while (entryWithMostWork.height > fork.height + 2) {
+          const previous = await this.getPrevious(entryWithMostWork)
+          this.invalidate(previous.hash)
+        }
+
+        // mark invalid first block of fork
+        const previous = await this.getPrevious(entryWithMostWork)
+        this.invalidate(previous.hash)
+
+        // check
+        assert(this.getPrevious(previous), fork)
+
+        return true
+      }
+    }
+
     // Blocks to disconnect.
     const disconnect = [];
     let entry = tip;
@@ -2209,7 +2240,7 @@ class Chain extends AsyncEmitter {
       targetTimespan = pow.targetTimespan_Version1;
 
     } else if ((prev.height + 1) < pow.blockHeight_Version3){
-      
+
       retargetInterval = pow.retargetInterval_Version2;
       averagingInterval = pow.averagingInterval_Version2;
       targetTimespan = pow.targetTimespan_Version2 * targetSpacing;
@@ -2247,10 +2278,10 @@ class Chain extends AsyncEmitter {
 
     // Back 6 block
     var back = averagingInterval - 1;
-    
+
     if (prev.height + 1 !== averagingInterval)
       back = averagingInterval;
-    
+
     let first = prev;
     for (let i = 0; i < back; i++){
       if (first)
diff --git a/lib/protocol/network.js b/lib/protocol/network.js
index 41448153..a74fbe36 100644
--- a/lib/protocol/network.js
+++ b/lib/protocol/network.js
@@ -58,6 +58,7 @@ class Network {
     this.maxFeeRate = options.maxFeeRate;
     this.selfConnect = options.selfConnect;
     this.requestMempool = options.requestMempool;
+    this.nlrLimit = options.nlrLimit;
     this.time = new TimeData();
 
     this.init();
diff --git a/lib/protocol/networks.js b/lib/protocol/networks.js
index 96a4fcb8..d1c137b4 100644
--- a/lib/protocol/networks.js
+++ b/lib/protocol/networks.js
@@ -563,6 +563,8 @@ main.selfConnect = false;
 
 main.requestMempool = false;
 
+main.nlrLimit = 100 // 100 * ~40s = ~66 minutes
+
 /*
  * Testnet (v3)
  * https://en.bitcoin.it/wiki/Testnet
@@ -800,6 +802,8 @@ testnet.selfConnect = false;
 
 testnet.requestMempool = false;
 
+testnet.nlrLimit = 50; // 50 * ~40s = ~33 minutes
+
 /*
  * Regtest
  */
@@ -1019,6 +1023,8 @@ regtest.selfConnect = true;
 
 regtest.requestMempool = true;
 
+regtest.nlrLimit = 10;
+
 /*
  * Simnet (btcd)
  */