diff --git a/src/init.cpp b/src/init.cpp
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1105,7 +1105,7 @@
     // a separate counter. Once we hit a gap (or if 0 doesn't exist) start
     // removing block files.
     int nContigCounter = 0;
-    for (const std::pair<std::string, fs::path> &item : mapBlockFiles) {
+    for (const std::pair<const std::string, fs::path> &item : mapBlockFiles) {
         if (atoi(item.first) == nContigCounter) {
             nContigCounter++;
             continue;
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -596,7 +596,8 @@
     UniValue localAddresses(UniValue::VARR);
     {
         LOCK(cs_mapLocalHost);
-        for (const std::pair<CNetAddr, LocalServiceInfo> &item : mapLocalHost) {
+        for (const std::pair<const CNetAddr, LocalServiceInfo> &item :
+             mapLocalHost) {
             UniValue rec(UniValue::VOBJ);
             rec.pushKV("address", item.first.ToString());
             rec.pushKV("port", item.second.nPort);
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -4373,7 +4373,7 @@
     // Calculate nChainWork
     std::vector<std::pair<int, CBlockIndex *>> vSortedByHeight;
     vSortedByHeight.reserve(mapBlockIndex.size());
-    for (const std::pair<uint256, CBlockIndex *> &item : mapBlockIndex) {
+    for (const std::pair<const uint256, CBlockIndex *> &item : mapBlockIndex) {
         CBlockIndex *pindex = item.second;
         vSortedByHeight.push_back(std::make_pair(pindex->nHeight, pindex));
     }
@@ -4466,7 +4466,7 @@
     // Check presence of blk files
     LogPrintf("Checking all blk files are present...\n");
     std::set<int> setBlkDataFiles;
-    for (const std::pair<uint256, CBlockIndex *> &item : mapBlockIndex) {
+    for (const std::pair<const uint256, CBlockIndex *> &item : mapBlockIndex) {
         CBlockIndex *pindex = item.second;
         if (pindex->nStatus.hasData()) {
             setBlkDataFiles.insert(pindex->nFile);
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -133,7 +133,7 @@
     entry.pushKV("time", wtx.GetTxTime());
     entry.pushKV("timereceived", (int64_t)wtx.nTimeReceived);
 
-    for (const std::pair<std::string, std::string> &item : wtx.mapValue) {
+    for (const std::pair<const std::string, std::string> &item : wtx.mapValue) {
         entry.pushKV(item.first, item.second);
     }
 }
@@ -444,7 +444,7 @@
 
     // Find all addresses that have the given account
     UniValue ret(UniValue::VARR);
-    for (const std::pair<CTxDestination, CAddressBookData> &item :
+    for (const std::pair<const CTxDestination, CAddressBookData> &item :
          pwallet->mapAddressBook) {
         const CTxDestination &dest = item.first;
         const std::string &strName = item.second.name;
@@ -804,7 +804,8 @@
 
     // Tally
     Amount nAmount = Amount::zero();
-    for (const std::pair<uint256, CWalletTx> &pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx> &pairWtx :
+         pwallet->mapWallet) {
         const CWalletTx &wtx = pairWtx.second;
 
         CValidationState state;
@@ -878,7 +879,8 @@
 
     // Tally
     Amount nAmount = Amount::zero();
-    for (const std::pair<uint256, CWalletTx> &pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx> &pairWtx :
+         pwallet->mapWallet) {
         const CWalletTx &wtx = pairWtx.second;
         CValidationState state;
         if (wtx.IsCoinBase() || !ContextualCheckTransactionForCurrentBlock(
@@ -1523,7 +1525,8 @@
 
     // Tally
     std::map<CTxDestination, tallyitem> mapTally;
-    for (const std::pair<uint256, CWalletTx> &pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx> &pairWtx :
+         pwallet->mapWallet) {
         const CWalletTx &wtx = pairWtx.second;
 
         CValidationState state;
@@ -2117,7 +2120,7 @@
     }
 
     std::map<std::string, Amount> mapAccountBalances;
-    for (const std::pair<CTxDestination, CAddressBookData> &entry :
+    for (const std::pair<const CTxDestination, CAddressBookData> &entry :
          pwallet->mapAddressBook) {
         // This address belongs to me
         if (IsMine(*pwallet, entry.first) & includeWatchonly) {
@@ -2125,7 +2128,8 @@
         }
     }
 
-    for (const std::pair<uint256, CWalletTx> &pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx> &pairWtx :
+         pwallet->mapWallet) {
         const CWalletTx &wtx = pairWtx.second;
         Amount nFee;
         std::string strSentAccount;
@@ -2159,7 +2163,7 @@
     }
 
     UniValue ret(UniValue::VOBJ);
-    for (const std::pair<std::string, Amount> &accountBalance :
+    for (const std::pair<const std::string, Amount> &accountBalance :
          mapAccountBalances) {
         ret.pushKV(accountBalance.first,
                    ValueFromAmount(accountBalance.second));
@@ -2329,7 +2333,8 @@
 
     UniValue transactions(UniValue::VARR);
 
-    for (const std::pair<uint256, CWalletTx> &pairWtx : pwallet->mapWallet) {
+    for (const std::pair<const uint256, CWalletTx> &pairWtx :
+         pwallet->mapWallet) {
         CWalletTx tx = pairWtx.second;
 
         if (depth == -1 || tx.GetDepthInMainChain() < depth) {
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3516,7 +3516,7 @@
         LOCK(cs_wallet);
 
         // Delete destdata tuples associated with address.
-        for (const std::pair<std::string, std::string> &item :
+        for (const std::pair<const std::string, std::string> &item :
              mapAddressBook[address].destdata) {
             WalletBatch(*database).EraseDestData(address, item.first);
         }
@@ -3933,7 +3933,7 @@
 CWallet::GetLabelAddresses(const std::string &label) const {
     LOCK(cs_wallet);
     std::set<CTxDestination> result;
-    for (const std::pair<CTxDestination, CAddressBookData> &item :
+    for (const std::pair<const CTxDestination, CAddressBookData> &item :
          mapAddressBook) {
         const CTxDestination &address = item.first;
         const std::string &strName = item.second.name;