diff --git a/src/miner.cpp b/src/miner.cpp
index bb568832a68..934ad90327d 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -501,6 +501,40 @@ CBlockTemplate* CreateNewBlock(CPubKey _pk,const CScript& _scriptPubKeyIn, int32
 
             // Size limits
             unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
+
+            // Opret spam limits
+            if (mapArgs.count("-opretmintxfee"))
+            {
+                CAmount n = 0;
+                CFeeRate opretMinFeeRate;
+                if (ParseMoney(mapArgs["-opretmintxfee"], n) && n > 0)
+                    opretMinFeeRate = CFeeRate(n);
+                else
+                    opretMinFeeRate = CFeeRate(400000); // default opretMinFeeRate (1 KMD per 250 Kb = 0.004 per 1 Kb = 400000 sat per 1 Kb)
+
+                bool fSpamTx = false;
+                unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
+                unsigned int nTxOpretSize = 0;
+
+                // calc total oprets size
+                BOOST_FOREACH(const CTxOut& txout, tx.vout) {
+                    if (txout.scriptPubKey.IsOpReturn()) {
+                        CScript::const_iterator it = txout.scriptPubKey.begin() + 1;
+                        opcodetype op;
+                        std::vector<uint8_t> opretData;
+                        if (txout.scriptPubKey.GetOp(it, op, opretData)) {
+                            //std::cerr << HexStr(opretData.begin(), opretData.end()) << std::endl;
+                            nTxOpretSize += opretData.size();
+                        }
+                    }
+                }
+
+                if ((nTxOpretSize > 256) && (feeRate < opretMinFeeRate)) fSpamTx = true;
+                // std::cerr << tx.GetHash().ToString() << " nTxSize." << nTxSize << " nTxOpretSize." << nTxOpretSize << " feeRate." << feeRate.ToString() << " opretMinFeeRate." << opretMinFeeRate.ToString() << " fSpamTx." << fSpamTx << std::endl;
+                if (fSpamTx) continue;
+                // std::cerr << tx.GetHash().ToString() << " vecPriority.size() = " << vecPriority.size() << std::endl;
+            }
+
             if (nBlockSize + nTxSize >= nBlockMaxSize-512) // room for extra autotx
             {
                 //fprintf(stderr,"nBlockSize %d + %d nTxSize >= %d nBlockMaxSize\n",(int32_t)nBlockSize,(int32_t)nTxSize,(int32_t)nBlockMaxSize);
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 3afb5c39534..00dc71408ac 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -78,7 +78,7 @@ int8_t StakedNotaryID(std::string &notaryname, char *Raddress);
 uint64_t komodo_notarypayamount(int32_t nHeight, int64_t notarycount);
 int32_t komodo_notaries(uint8_t pubkeys[64][33],int32_t height,uint32_t timestamp);
 
-#define KOMODO_VERSION "0.5.1"
+#define KOMODO_VERSION "0.5.2"
 #define VERUS_VERSION "0.4.0g"
 extern uint16_t ASSETCHAINS_P2PPORT,ASSETCHAINS_RPCPORT;
 extern uint32_t ASSETCHAINS_CC;
diff --git a/src/version.h b/src/version.h
index 3cad9b6158a..81624e423b3 100644
--- a/src/version.h
+++ b/src/version.h
@@ -24,7 +24,7 @@
  * network protocol versioning
  */
 
-static const int PROTOCOL_VERSION = 170008;
+static const int PROTOCOL_VERSION = 170009;
 
 //! initial proto version, to be increased after version/verack negotiation
 static const int INIT_PROTO_VERSION = 209;