diff --git a/src/core_read.cpp b/src/core_read.cpp
index 4a1359901..06a4a9fa0 100644
--- a/src/core_read.cpp
+++ b/src/core_read.cpp
@@ -1,295 +1,295 @@
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <core_io.h>
 
 #include <primitives/block.h>
 #include <primitives/transaction.h>
 #include <psbt.h>
 #include <script/script.h>
 #include <script/sign.h>
 #include <serialize.h>
 #include <streams.h>
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <version.h>
 
 #include <univalue.h>
 
 #include <boost/algorithm/string/classification.hpp>
-#include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/split.hpp>
 
 #include <algorithm>
 #include <string>
 
 CScript ParseScript(const std::string &s) {
     CScript result;
 
     static std::map<std::string, opcodetype> mapOpNames;
 
     if (mapOpNames.empty()) {
         for (int op = 0; op < FIRST_UNDEFINED_OP_VALUE; op++) {
             if (op < OP_PUSHDATA1) {
                 continue;
             }
 
             std::string strName = GetOpName(static_cast<opcodetype>(op));
             if (strName == "OP_UNKNOWN") {
                 continue;
             }
 
             mapOpNames[strName] = static_cast<opcodetype>(op);
             // Convenience: OP_ADD and just ADD are both recognized:
-            boost::algorithm::replace_first(strName, "OP_", "");
-            mapOpNames[strName] = static_cast<opcodetype>(op);
+            if (strName.compare(0, 3, "OP_") == 0) {
+                mapOpNames[strName.substr(3)] = static_cast<opcodetype>(op);
+            }
         }
     }
 
     std::vector<std::string> words;
     boost::algorithm::split(words, s, boost::algorithm::is_any_of(" \t\n"),
                             boost::algorithm::token_compress_on);
 
     size_t push_size = 0, next_push_size = 0;
     size_t script_size = 0;
     // Deal with PUSHDATA1 operation with some more hacks.
     size_t push_data_size = 0;
 
     for (const auto &w : words) {
         if (w.empty()) {
             // Empty string, ignore. (boost::split given '' will return one
             // word)
             continue;
         }
 
         // Update script size.
         script_size = result.size();
 
         // Make sure we keep track of the size of push operations.
         push_size = next_push_size;
         next_push_size = 0;
 
         // Decimal numbers
         if (std::all_of(w.begin(), w.end(), ::IsDigit) ||
             (w.front() == '-' && w.size() > 1 &&
              std::all_of(w.begin() + 1, w.end(), ::IsDigit))) {
             // Number
             int64_t n = atoi64(w);
 
             // limit the range of numbers ParseScript accepts in decimal
             // since numbers outside -0xFFFFFFFF...0xFFFFFFFF are illegal in
             // scripts
             if (n > int64_t{0xffffffff} || n < -1 * int64_t{0xffffffff}) {
                 throw std::runtime_error("script parse error: decimal numeric "
                                          "value only allowed in the "
                                          "range -0xFFFFFFFF...0xFFFFFFFF");
             }
 
             result << n;
             goto next;
         }
 
         // Hex Data
         if (w.substr(0, 2) == "0x" && w.size() > 2) {
             if (!IsHex(std::string(w.begin() + 2, w.end()))) {
                 // Should only arrive here for improperly formatted hex values
                 throw std::runtime_error("Hex numbers expected to be formatted "
                                          "in full-byte chunks (ex: 0x00 "
                                          "instead of 0x0)");
             }
 
             // Raw hex data, inserted NOT pushed onto stack:
             std::vector<uint8_t> raw =
                 ParseHex(std::string(w.begin() + 2, w.end()));
 
             result.insert(result.end(), raw.begin(), raw.end());
             goto next;
         }
 
         if (w.size() >= 2 && w.front() == '\'' && w.back() == '\'') {
             // Single-quoted string, pushed as data. NOTE: this is poor-man's
             // parsing, spaces/tabs/newlines in single-quoted strings won't
             // work.
             std::vector<uint8_t> value(w.begin() + 1, w.end() - 1);
             result << value;
             goto next;
         }
 
         if (mapOpNames.count(w)) {
             // opcode, e.g. OP_ADD or ADD:
             opcodetype op = mapOpNames[w];
 
             result << op;
             goto next;
         }
 
         throw std::runtime_error("Error parsing script: " + s);
 
     next:
         size_t size_change = result.size() - script_size;
 
         // If push_size is set, ensure have added the right amount of stuff.
         if (push_size != 0 && size_change != push_size) {
             throw std::runtime_error(
                 "Wrong number of bytes being pushed. Expected:" +
                 ToString(push_size) + " Pushed:" + ToString(size_change));
         }
 
         // If push_size is set, and we have push_data_size set, then we have a
         // PUSHDATAX opcode.  We need to read it's push size as a LE value for
         // the next iteration of this loop.
         if (push_size != 0 && push_data_size != 0) {
             auto offset = &result[script_size];
 
             // Push data size is not a CScriptNum (Because it is
             // 2's-complement instead of 1's complement).  We need to use
             // ReadLE(N) instead of converting to a CScriptNum.
             if (push_data_size == 1) {
                 next_push_size = *offset;
             } else if (push_data_size == 2) {
                 next_push_size = ReadLE16(offset);
             } else if (push_data_size == 4) {
                 next_push_size = ReadLE32(offset);
             }
 
             push_data_size = 0;
         }
 
         // If push_size is unset, but size_change is 1, that means we have an
         // opcode in the form of `0x00` or <opcodename>.  We will check to see
         // if it is a push operation and set state accordingly
         if (push_size == 0 && size_change == 1) {
             opcodetype op = opcodetype(*result.rbegin());
 
             // If we have what looks like an immediate push, figure out its
             // size.
             if (op < OP_PUSHDATA1) {
                 next_push_size = op;
                 continue;
             }
 
             switch (op) {
                 case OP_PUSHDATA1:
                     push_data_size = next_push_size = 1;
                     break;
                 case OP_PUSHDATA2:
                     push_data_size = next_push_size = 2;
                     break;
                 case OP_PUSHDATA4:
                     push_data_size = next_push_size = 4;
                     break;
                 default:
                     break;
             }
         }
     }
 
     return result;
 }
 
 bool DecodeHexTx(CMutableTransaction &tx, const std::string &strHexTx) {
     if (!IsHex(strHexTx)) {
         return false;
     }
 
     std::vector<uint8_t> txData(ParseHex(strHexTx));
 
     CDataStream ssData(txData, SER_NETWORK, PROTOCOL_VERSION);
     try {
         ssData >> tx;
         if (ssData.eof()) {
             return true;
         }
     } catch (const std::exception &e) {
         // Fall through.
     }
 
     return false;
 }
 
 bool DecodeHexBlockHeader(CBlockHeader &header, const std::string &hex_header) {
     if (!IsHex(hex_header)) {
         return false;
     }
 
     const std::vector<uint8_t> header_data{ParseHex(hex_header)};
     CDataStream ser_header(header_data, SER_NETWORK, PROTOCOL_VERSION);
     try {
         ser_header >> header;
     } catch (const std::exception &) {
         return false;
     }
     return true;
 }
 
 bool DecodeHexBlk(CBlock &block, const std::string &strHexBlk) {
     if (!IsHex(strHexBlk)) {
         return false;
     }
 
     std::vector<uint8_t> blockData(ParseHex(strHexBlk));
     CDataStream ssBlock(blockData, SER_NETWORK, PROTOCOL_VERSION);
     try {
         ssBlock >> block;
     } catch (const std::exception &) {
         return false;
     }
 
     return true;
 }
 
 bool ParseHashStr(const std::string &strHex, uint256 &result) {
     if ((strHex.size() != 64) || !IsHex(strHex)) {
         return false;
     }
 
     result.SetHex(strHex);
     return true;
 }
 
 std::vector<uint8_t> ParseHexUV(const UniValue &v, const std::string &strName) {
     std::string strHex;
     if (v.isStr()) {
         strHex = v.getValStr();
     }
 
     if (!IsHex(strHex)) {
         throw std::runtime_error(
             strName + " must be hexadecimal string (not '" + strHex + "')");
     }
 
     return ParseHex(strHex);
 }
 
 SigHashType ParseSighashString(const UniValue &sighash) {
     SigHashType sigHashType = SigHashType().withForkId();
     if (!sighash.isNull()) {
         static std::map<std::string, int> map_sighash_values = {
             {"ALL", SIGHASH_ALL},
             {"ALL|ANYONECANPAY", SIGHASH_ALL | SIGHASH_ANYONECANPAY},
             {"ALL|FORKID", SIGHASH_ALL | SIGHASH_FORKID},
             {"ALL|FORKID|ANYONECANPAY",
              SIGHASH_ALL | SIGHASH_FORKID | SIGHASH_ANYONECANPAY},
             {"NONE", SIGHASH_NONE},
             {"NONE|ANYONECANPAY", SIGHASH_NONE | SIGHASH_ANYONECANPAY},
             {"NONE|FORKID", SIGHASH_NONE | SIGHASH_FORKID},
             {"NONE|FORKID|ANYONECANPAY",
              SIGHASH_NONE | SIGHASH_FORKID | SIGHASH_ANYONECANPAY},
             {"SINGLE", SIGHASH_SINGLE},
             {"SINGLE|ANYONECANPAY", SIGHASH_SINGLE | SIGHASH_ANYONECANPAY},
             {"SINGLE|FORKID", SIGHASH_SINGLE | SIGHASH_FORKID},
             {"SINGLE|FORKID|ANYONECANPAY",
              SIGHASH_SINGLE | SIGHASH_FORKID | SIGHASH_ANYONECANPAY},
         };
         std::string strHashType = sighash.get_str();
         const auto &it = map_sighash_values.find(strHashType);
         if (it != map_sighash_values.end()) {
             sigHashType = SigHashType(it->second);
         } else {
             throw std::runtime_error(strHashType +
                                      " is not a valid sighash parameter.");
         }
     }
     return sigHashType;
 }