diff --git a/src/chainparams.cpp b/src/chainparams.cpp
index 6726c07f8..90e91172f 100644
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -99,10 +99,10 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = 1517356801; // January 31st, 2018
 
         // The best chain should have at least this much work.
-        consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000000000000000000000100000");
+        consensus.nMinimumChainWork  = uint256S("0x0000000000000000000000000000000000000000000000000000000001000000");
 
         // By default assume that the signatures in ancestors of this block are valid.
-        consensus.defaultAssumeValid = uint256S("0x66f49ad85624c33e4fd61aa45c54012509ed4a53308908dd07f56346c7939273");
+        consensus.defaultAssumeValid = uint256S("0x00");
 
         /**
          * The message start string is designed to be unlikely to occur in normal data.
@@ -118,7 +118,7 @@ public:
 
         const uint32_t genesisBlockReward = 0.00001 * COIN; // A small reward for the core developers :-)
         //TODO: target: 0x1e0fffff, update timestampe and nonce.
-        genesis = CreateGenesisBlock(1553145843, 1621, 0x1f0ffff0, 1, genesisBlockReward);
+        genesis = CreateGenesisBlock(1553145843, 1621, 0x1e0fffff, 1, genesisBlockReward);
         consensus.hashGenesisBlock = genesis.GetHash();
         assert(consensus.hashGenesisBlock == uint256S("0x2f6d82a919bfc055f9e66e82bd613050cb835f969563f217737c9ef631668f6c"));
         assert(genesis.hashMerkleRoot == uint256S("0x285139132ff0b33d399aae61053d19b34fe8e483053142d530d62d90881183c9"));
@@ -194,10 +194,10 @@ public:
         consensus.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout = 1517356801; // January 31st, 2018
 
         // The best chain should have at least this much work.
-        consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000000000000000000000001000");
+        consensus.nMinimumChainWork  = uint256S("0x0000000000000000000000000000000000000000000000000000000000001000");
 
         // By default assume that the signatures in ancestors of this block are valid.
-        consensus.defaultAssumeValid = uint256S("0x1efb29c8187d5a496a33377941d1df415169c3ce5d8c05d055f25b683ec3f9a3");
+        consensus.defaultAssumeValid = uint256S("0x00");
 
         pchMessageStart[0] = 0xfe;
         pchMessageStart[1] = 0xec;
diff --git a/src/primitives/block.cpp b/src/primitives/block.cpp
index 0f273a820..2e26b35bf 100644
--- a/src/primitives/block.cpp
+++ b/src/primitives/block.cpp
@@ -22,9 +22,21 @@ uint256 CBlockHeader::GetOriginalBlockHash() const
     return hashWriter.GetHash();
 }
 
+// prev_id of CN header is used to store the kevacoin block hash.
+// The value of prev_id and block hash must be the same to prove
+// that PoW has been properly done.
+bool CBlockHeader::isCNConsistent() const
+{
+    return (GetOriginalBlockHash() == cnHeader.prev_id);
+}
+
 uint256 CBlockHeader::GetHash() const
 {
     uint256 thash;
+    if (!isCNConsistent()) {
+        memset(thash.begin(), 0xff, thash.size());
+        return thash;
+    }
     cryptonote::blobdata blob = cryptonote::t_serializable_object_to_blob(cnHeader);
     cn_fast_hash(blob.data(), blob.size(), BEGIN(thash));
     return thash;
@@ -33,10 +45,7 @@ uint256 CBlockHeader::GetHash() const
 uint256 CBlockHeader::GetPoWHash() const
 {
     uint256 thash;
-    // prev_id of CN header is used to store the kevacoin block hash.
-    // The value of prev_id and block hash must be the same to prove
-    // that PoW has been properly done.
-    if (GetOriginalBlockHash() != cnHeader.prev_id) {
+    if (!isCNConsistent()) {
         memset(thash.begin(), 0xff, thash.size());
         return thash;
     }
diff --git a/src/primitives/block.h b/src/primitives/block.h
index 566b3e44e..946c80de3 100644
--- a/src/primitives/block.h
+++ b/src/primitives/block.h
@@ -184,6 +184,8 @@ public:
         legacyMode = legacy;
     }
 
+    bool isCNConsistent() const;
+
     bool isLegacy()
     {
         return legacyMode;