diff --git a/src/net_processing.cpp b/src/net_processing.cpp
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1050,7 +1050,7 @@
     // Erase orphan transactions included or precluded by this block
     if (vOrphanErase.size()) {
         int nErased = 0;
-        for (uint256 &orphanId : vOrphanErase) {
+        for (const uint256 &orphanId : vOrphanErase) {
             nErased += EraseOrphanTx(orphanId);
         }
         LogPrint(BCLog::MEMPOOL,
diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -439,7 +439,7 @@
 
 #ifdef ENABLE_WALLET
     window->removeAllWallets();
-    for (WalletModel *walletModel : m_wallet_models) {
+    for (const WalletModel *walletModel : m_wallet_models) {
         delete walletModel;
     }
     m_wallet_models.clear();
diff --git a/src/qt/peertablemodel.cpp b/src/qt/peertablemodel.cpp
--- a/src/qt/peertablemodel.cpp
+++ b/src/qt/peertablemodel.cpp
@@ -61,7 +61,7 @@
             interfaces::Node::NodesStats nodes_stats;
             node.getNodesStats(nodes_stats);
             cachedNodeStats.reserve(nodes_stats.size());
-            for (auto &node_stats : nodes_stats) {
+            for (const auto &node_stats : nodes_stats) {
                 CNodeCombinedStats stats;
                 stats.nodeStats = std::get<0>(node_stats);
                 stats.fNodeStateStatsAvailable = std::get<1>(node_stats);
diff --git a/src/qt/splashscreen.cpp b/src/qt/splashscreen.cpp
--- a/src/qt/splashscreen.cpp
+++ b/src/qt/splashscreen.cpp
@@ -217,7 +217,7 @@
     // Disconnect signals from client
     m_handler_init_message->disconnect();
     m_handler_show_progress->disconnect();
-    for (auto &handler : m_connected_wallet_handlers) {
+    for (const auto &handler : m_connected_wallet_handlers) {
         handler->disconnect();
     }
     m_connected_wallet_handlers.clear();
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -476,7 +476,7 @@
     const CTxMemPool::txiter &it = g_mempool.mapTx.find(tx.GetId());
     const CTxMemPool::setEntries &setChildren =
         g_mempool.GetMemPoolChildren(it);
-    for (const CTxMemPool::txiter &childiter : setChildren) {
+    for (CTxMemPool::txiter childiter : setChildren) {
         spent.push_back(childiter->GetTx().GetId().ToString());
     }
 
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -207,7 +207,7 @@
             obj.pushKV("synced_headers", statestats.nSyncHeight);
             obj.pushKV("synced_blocks", statestats.nCommonHeight);
             UniValue heights(UniValue::VARR);
-            for (int height : statestats.vHeightInFlight) {
+            for (const int height : statestats.vHeightInFlight) {
                 heights.push_back(height);
             }
             obj.pushKV("inflight", heights);
diff --git a/src/test/cuckoocache_tests.cpp b/src/test/cuckoocache_tests.cpp
--- a/src/test/cuckoocache_tests.cpp
+++ b/src/test/cuckoocache_tests.cpp
@@ -70,12 +70,12 @@
      */
     std::vector<uint256> hashes_insert_copy = hashes;
     /** Do the insert */
-    for (uint256 &h : hashes_insert_copy) {
+    for (const uint256 &h : hashes_insert_copy) {
         set.insert(h);
     }
     /** Count the hits */
     uint32_t count = 0;
-    for (uint256 &h : hashes) {
+    for (const uint256 &h : hashes) {
         count += set.contains(h, false);
     }
     double hit_rate = double(count) / double(n_insert);
@@ -327,7 +327,7 @@
             for (uint32_t i = n_insert - (n_insert / 4); i < n_insert; ++i) {
                 reads.push_back(inserts[i]);
             }
-            for (auto h : inserts) {
+            for (const auto &h : inserts) {
                 c.insert(h);
             }
         }
diff --git a/src/test/dbwrapper_tests.cpp b/src/test/dbwrapper_tests.cpp
--- a/src/test/dbwrapper_tests.cpp
+++ b/src/test/dbwrapper_tests.cpp
@@ -224,7 +224,7 @@
         }
     }
 
-    for (int seek_start : {0x00, 0x80}) {
+    for (const int seek_start : {0x00, 0x80}) {
         it->Seek((uint8_t)seek_start);
         for (unsigned int x = seek_start; x < 255; ++x) {
             uint8_t key;
diff --git a/src/test/getarg_tests.cpp b/src/test/getarg_tests.cpp
--- a/src/test/getarg_tests.cpp
+++ b/src/test/getarg_tests.cpp
@@ -25,7 +25,7 @@
 
     // Convert to char*:
     std::vector<const char *> vecChar;
-    for (std::string &s : vecArg) {
+    for (const std::string &s : vecArg) {
         vecChar.push_back(s.c_str());
     }
 
diff --git a/src/test/key_io_tests.cpp b/src/test/key_io_tests.cpp
--- a/src/test/key_io_tests.cpp
+++ b/src/test/key_io_tests.cpp
@@ -155,8 +155,9 @@
         std::string exp_base58string = test[0].get_str();
 
         // must be invalid as public and as private key
-        for (auto chain : {CBaseChainParams::MAIN, CBaseChainParams::TESTNET,
-                           CBaseChainParams::REGTEST}) {
+        for (const auto &chain :
+             {CBaseChainParams::MAIN, CBaseChainParams::TESTNET,
+              CBaseChainParams::REGTEST}) {
             SelectParams(chain);
             destination = DecodeLegacyAddr(exp_base58string, Params());
             BOOST_CHECK_MESSAGE(!IsValidDestination(destination),
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -243,7 +243,7 @@
         }
 
         const setEntries &setMemPoolParents = GetMemPoolParents(stageit);
-        for (const txiter &phash : setMemPoolParents) {
+        for (txiter phash : setMemPoolParents) {
             // If this is a new ancestor, add it.
             if (setAncestors.count(phash) == 0) {
                 parentHashes.insert(phash);
@@ -513,7 +513,7 @@
         stage.erase(it);
 
         const setEntries &setChildren = GetMemPoolChildren(it);
-        for (const txiter &childiter : setChildren) {
+        for (txiter childiter : setChildren) {
             if (!setDescendants.count(childiter)) {
                 stage.insert(childiter);
             }
@@ -1046,7 +1046,7 @@
                               MemPoolRemovalReason reason) {
     AssertLockHeld(cs);
     UpdateForRemoveFromMempool(stage, updateDescendants);
-    for (const txiter &it : stage) {
+    for (txiter it : stage) {
         removeUnchecked(it, reason);
     }
 }
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -5020,7 +5020,7 @@
     setDirtyBlockIndex.clear();
     setDirtyFileInfo.clear();
 
-    for (BlockMap::value_type &entry : mapBlockIndex) {
+    for (const BlockMap::value_type &entry : mapBlockIndex) {
         delete entry.second;
     }
 
@@ -5270,7 +5270,7 @@
 
     // Build forward-pointing map of the entire block tree.
     std::multimap<CBlockIndex *, CBlockIndex *> forward;
-    for (auto &entry : mapBlockIndex) {
+    for (const auto &entry : mapBlockIndex) {
         forward.emplace(entry.second->pprev, entry.second);
     }
 
diff --git a/src/wallet/db.cpp b/src/wallet/db.cpp
--- a/src/wallet/db.cpp
+++ b/src/wallet/db.cpp
@@ -548,7 +548,7 @@
             // be implemented, so no equality checks are needed at all. (Newer
             // versions of BDB have an set_lk_exclusive method for this
             // purpose, but the older version we use does not.)
-            for (auto &dbenv : g_dbenvs) {
+            for (const auto &dbenv : g_dbenvs) {
                 CheckUniqueFileid(dbenv.second, strFilename, *pdb_temp);
             }
 
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -3184,7 +3184,7 @@
 
     UniValue ret(UniValue::VARR);
 
-    for (COutPoint &output : vOutpts) {
+    for (const COutPoint &output : vOutpts) {
         UniValue o(UniValue::VOBJ);
 
         o.pushKV("txid", output.GetTxId().GetHex());
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1647,7 +1647,7 @@
     // Look up the inputs.  We should have already checked that this transaction
     // IsAllFromMe(ISMINE_SPENDABLE), so every input should already be in our
     // wallet, with a valid index into the vout array, and the ability to sign.
-    for (auto &input : tx.vin) {
+    for (const auto &input : tx.vin) {
         const auto mi = wallet->mapWallet.find(input.prevout.GetTxId());
         if (mi == wallet->mapWallet.end()) {
             return -1;
@@ -1924,7 +1924,7 @@
     }
 
     // Try to add wallet transactions to memory pool.
-    for (std::pair<const int64_t, CWalletTx *> &item : mapSorted) {
+    for (const auto &item : mapSorted) {
         CWalletTx &wtx = *(item.second);
         CValidationState state;
         wtx.AcceptToMemoryPool(maxTxFee, state);
@@ -2207,7 +2207,7 @@
         mapSorted.insert(std::make_pair(wtx.nTimeReceived, &wtx));
     }
 
-    for (std::pair<const unsigned int, CWalletTx *> &item : mapSorted) {
+    for (const auto &item : mapSorted) {
         CWalletTx &wtx = *item.second;
         if (wtx.RelayWalletTransaction(connman)) {
             result.push_back(wtx.GetId());
@@ -2528,7 +2528,7 @@
 
     AvailableCoins(availableCoins);
 
-    for (auto &coin : availableCoins) {
+    for (const auto &coin : availableCoins) {
         CTxDestination address;
         if (coin.fSpendable &&
             ExtractDestination(
@@ -3896,7 +3896,7 @@
         // Make a set of all the groups hit by this new group.
         std::set<std::set<CTxDestination> *> hits;
         std::map<CTxDestination, std::set<CTxDestination> *>::iterator it;
-        for (CTxDestination address : _grouping) {
+        for (const CTxDestination &address : _grouping) {
             if ((it = setmap.find(address)) != setmap.end()) {
                 hits.insert((*it).second);
             }
@@ -3913,13 +3913,13 @@
         uniqueGroupings.insert(merged);
 
         // Update setmap.
-        for (CTxDestination element : *merged) {
+        for (const CTxDestination &element : *merged) {
             setmap[element] = merged;
         }
     }
 
     std::set<std::set<CTxDestination>> ret;
-    for (std::set<CTxDestination> *uniqueGrouping : uniqueGroupings) {
+    for (const std::set<CTxDestination> *uniqueGrouping : uniqueGroupings) {
         ret.insert(*uniqueGrouping);
         delete uniqueGrouping;
     }