diff --git a/src/addrman.cpp b/src/addrman.cpp
index 7636c6bad2..ed7fccc0ff 100644
--- a/src/addrman.cpp
+++ b/src/addrman.cpp
@@ -617,7 +617,7 @@ CAddrInfo CAddrMan::SelectTriedCollision_()
         return CAddrInfo();
     }
 
-    CAddrInfo& newInfo = mapInfo[id_new];
+    const CAddrInfo& newInfo = mapInfo[id_new];
 
     // which tried bucket to move the entry to
     int tried_bucket = newInfo.GetTriedBucket(nKey, m_asmap);
diff --git a/src/logging.cpp b/src/logging.cpp
index 35e0754f20..4ddcf1d930 100644
--- a/src/logging.cpp
+++ b/src/logging.cpp
@@ -174,7 +174,7 @@ bool GetLogCategory(BCLog::LogFlags& flag, const std::string& str)
     return false;
 }
 
-std::vector<LogCategory> BCLog::Logger::LogCategoriesList()
+std::vector<LogCategory> BCLog::Logger::LogCategoriesList() const
 {
     std::vector<LogCategory> ret;
     for (const CLogCategoryDesc& category_desc : LogCategories) {
diff --git a/src/logging.h b/src/logging.h
index 7e646ef67a..9efecc7c12 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -135,9 +135,9 @@ namespace BCLog {
 
         bool WillLogCategory(LogFlags category) const;
         /** Returns a vector of the log categories */
-        std::vector<LogCategory> LogCategoriesList();
+        std::vector<LogCategory> LogCategoriesList() const;
         /** Returns a string with the log categories */
-        std::string LogCategoriesString()
+        std::string LogCategoriesString() const
         {
             return Join(LogCategoriesList(), ", ", [&](const LogCategory& i) { return i.category; });
         };
diff --git a/src/miner.cpp b/src/miner.cpp
index 73437df58e..6e8daee8a6 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -263,7 +263,7 @@ bool BlockAssembler::TestPackage(uint64_t packageSize, int64_t packageSigOpsCost
 // - transaction finality (locktime)
 // - premature witness (in case segwit transactions are added to mempool before
 //   segwit activation)
-bool BlockAssembler::TestPackageTransactions(const CTxMemPool::setEntries& package)
+bool BlockAssembler::TestPackageTransactions(const CTxMemPool::setEntries& package) const
 {
     for (CTxMemPool::txiter it : package) {
         if (!IsFinalTx(it->GetTx(), nHeight, nLockTimeCutoff))
diff --git a/src/miner.h b/src/miner.h
index 8510983419..8f5c6ad63b 100644
--- a/src/miner.h
+++ b/src/miner.h
@@ -185,7 +185,7 @@ private:
       * locktime, premature-witness, serialized size (if necessary)
       * These checks should always succeed, and they're here
       * only as an extra check in case of suboptimal node configuration */
-    bool TestPackageTransactions(const CTxMemPool::setEntries& package);
+    bool TestPackageTransactions(const CTxMemPool::setEntries& package) const;
     /** Return true if given transaction from mapTx has already been evaluated,
       * or if the transaction's cached data in mapTx is incorrect. */
     bool SkipMapTxEntry(CTxMemPool::txiter it, indexed_modified_transaction_set& mapModifiedTx, CTxMemPool::setEntries& failedTx) EXCLUSIVE_LOCKS_REQUIRED(m_mempool.cs);
diff --git a/src/net.cpp b/src/net.cpp
index ebd918d63e..e6ccc32d89 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1206,7 +1206,7 @@ void CConnman::NotifyNumConnectionsChanged()
     }
 }
 
-void CConnman::InactivityCheck(CNode *pnode)
+void CConnman::InactivityCheck(CNode *pnode) const
 {
     int64_t nTime = GetSystemTimeInSeconds();
     if (nTime - pnode->nTimeConnected > m_peer_connect_timeout)
diff --git a/src/net.h b/src/net.h
index cbc2a3dc38..0a3ad36898 100644
--- a/src/net.h
+++ b/src/net.h
@@ -420,7 +420,7 @@ private:
     void AcceptConnection(const ListenSocket& hListenSocket);
     void DisconnectNodes();
     void NotifyNumConnectionsChanged();
-    void InactivityCheck(CNode *pnode);
+    void InactivityCheck(CNode *pnode) const;
     bool GenerateSelectSet(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set);
     void SocketEvents(std::set<SOCKET> &recv_set, std::set<SOCKET> &send_set, std::set<SOCKET> &error_set);
     void SocketHandler();
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index e86b8834c6..163485681c 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -68,7 +68,7 @@ NodeContext& EnsureNodeContext(const util::Ref& context)
 
 CTxMemPool& EnsureMemPool(const util::Ref& context)
 {
-    NodeContext& node = EnsureNodeContext(context);
+    const NodeContext& node = EnsureNodeContext(context);
     if (!node.mempool) {
         throw JSONRPCError(RPC_CLIENT_MEMPOOL_DISABLED, "Mempool disabled or instance not found");
     }
@@ -77,7 +77,7 @@ CTxMemPool& EnsureMemPool(const util::Ref& context)
 
 ChainstateManager& EnsureChainman(const util::Ref& context)
 {
-    NodeContext& node = EnsureNodeContext(context);
+    const NodeContext& node = EnsureNodeContext(context);
     if (!node.chainman) {
         throw JSONRPCError(RPC_INTERNAL_ERROR, "Node chainman not found");
     }
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 408f485131..17642223ea 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -319,8 +319,8 @@ private:
     uint32_t m_first_false_pos = NO_FALSE;
 
 public:
-    bool empty() { return m_stack_size == 0; }
-    bool all_true() { return m_first_false_pos == NO_FALSE; }
+    bool empty() const { return m_stack_size == 0; }
+    bool all_true() const { return m_first_false_pos == NO_FALSE; }
     void push_back(bool f)
     {
         if (m_first_false_pos == NO_FALSE && !f) {
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 940bd6a65e..c635149fc8 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -407,7 +407,7 @@ bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, C
 bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
 {
     assert(nIn < txTo.vin.size());
-    CTxIn& txin = txTo.vin[nIn];
+    const CTxIn& txin = txTo.vin[nIn];
     assert(txin.prevout.n < txFrom.vout.size());
     const CTxOut& txout = txFrom.vout[txin.prevout.n];
 
diff --git a/src/test/checkqueue_tests.cpp b/src/test/checkqueue_tests.cpp
index 768eb08ba8..f7cb694253 100644
--- a/src/test/checkqueue_tests.cpp
+++ b/src/test/checkqueue_tests.cpp
@@ -26,7 +26,7 @@ static const unsigned int QUEUE_BATCH_SIZE = 128;
 static const int SCRIPT_CHECK_THREADS = 3;
 
 struct FakeCheck {
-    bool operator()()
+    bool operator()() const
     {
         return true;
     }
@@ -47,7 +47,7 @@ struct FailingCheck {
     bool fails;
     FailingCheck(bool _fails) : fails(_fails){};
     FailingCheck() : fails(true){};
-    bool operator()()
+    bool operator()() const
     {
         return !fails;
     }
@@ -76,7 +76,7 @@ struct UniqueCheck {
 struct MemoryCheck {
     static std::atomic<size_t> fake_allocated_memory;
     bool b {false};
-    bool operator()()
+    bool operator()() const
     {
         return true;
     }
@@ -107,7 +107,7 @@ struct FrozenCleanupCheck {
     // Freezing can't be the default initialized behavior given how the queue
     // swaps in default initialized Checks.
     bool should_freeze {false};
-    bool operator()()
+    bool operator()() const
     {
         return true;
     }
diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
index 68804efebf..9a4657cc9b 100644
--- a/src/test/util/setup_common.cpp
+++ b/src/test/util/setup_common.cpp
@@ -264,12 +264,12 @@ TestChain100Setup::~TestChain100Setup()
     gArgs.ForceSetArg("-segwitheight", "0");
 }
 
-CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CMutableTransaction& tx)
+CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CMutableTransaction& tx) const
 {
     return FromTx(MakeTransactionRef(tx));
 }
 
-CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CTransactionRef& tx)
+CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CTransactionRef& tx) const
 {
     return CTxMemPoolEntry(tx, nFee, nTime, nHeight,
                            spendsCoinbase, sigOpCost, lp, setPeginsSpent);
diff --git a/src/test/util/setup_common.h b/src/test/util/setup_common.h
index 38552d45b4..ad3e0e3ce7 100644
--- a/src/test/util/setup_common.h
+++ b/src/test/util/setup_common.h
@@ -147,8 +147,8 @@ struct TestMemPoolEntryHelper
         nFee(0), nTime(0), nHeight(1),
         spendsCoinbase(false), sigOpCost(4) { }
 
-    CTxMemPoolEntry FromTx(const CMutableTransaction& tx);
-    CTxMemPoolEntry FromTx(const CTransactionRef& tx);
+    CTxMemPoolEntry FromTx(const CMutableTransaction& tx) const;
+    CTxMemPoolEntry FromTx(const CTransactionRef& tx) const;
 
     // Change the default value
     TestMemPoolEntryHelper &Fee(CAmount _fee) { nFee = _fee; return *this; }
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 881f0ca6c0..1d10a618e6 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -23,7 +23,7 @@
 
 CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFee,
                                  int64_t _nTime, unsigned int _entryHeight,
-                                 bool _spendsCoinbase, int64_t _sigOpsCost, LockPoints lp, std::set<std::pair<uint256, COutPoint>>& _setPeginsSpent)
+                                 bool _spendsCoinbase, int64_t _sigOpsCost, LockPoints lp, const std::set<std::pair<uint256, COutPoint>>& _setPeginsSpent)
     : tx(_tx), nFee(_nFee), nTxWeight(GetTransactionWeight(*tx)), nUsageSize(RecursiveDynamicUsage(tx)), nTime(_nTime), entryHeight(_entryHeight),
     spendsCoinbase(_spendsCoinbase), sigOpCost(_sigOpsCost), lockPoints(lp), m_epoch(0),
     setPeginsSpent(_setPeginsSpent)
diff --git a/src/txmempool.h b/src/txmempool.h
index 412a7020e9..792abf356f 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -116,7 +116,7 @@ public:
                     int64_t _nTime, unsigned int _entryHeight,
                     bool spendsCoinbase,
                     int64_t nSigOpsCost, LockPoints lp,
-                    std::set<std::pair<uint256, COutPoint>>& setPeginsSpent);
+                    const std::set<std::pair<uint256, COutPoint>>& setPeginsSpent);
 
     const CTransaction& GetTx() const { return *this->tx; }
     CTransactionRef GetSharedTx() const { return this->tx; }
diff --git a/src/validation.cpp b/src/validation.cpp
index 1b2b602826..736bf883d8 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -681,7 +681,7 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     // Used when checking peg-ins
     std::vector<std::pair<CScript, CScript>> fedpegscripts = GetValidFedpegScripts(::ChainActive().Tip(), chainparams.GetConsensus(), true /* nextblock_validation */);
 
-    CCoinsViewCache& coins_cache = ::ChainstateActive().CoinsTip();
+    const CCoinsViewCache& coins_cache = ::ChainstateActive().CoinsTip();
     // do all inputs exist?
     for (unsigned int i = 0; i < tx.vin.size(); i++) {
         const CTxIn& txin = tx.vin[i];
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index 359c348ab6..54f50cdc43 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -273,7 +273,7 @@ Result CommitTransaction(CWallet& wallet, const uint256& txid, CMutableTransacti
         errors.push_back(Untranslated("Invalid or non-wallet transaction id"));
         return Result::MISC_ERROR;
     }
-    CWalletTx& oldWtx = it->second;
+    const CWalletTx& oldWtx = it->second;
 
     // make sure the transaction still has no descendants and hasn't been mined in the meantime
     Result result = PreconditionChecks(wallet, oldWtx, errors);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index c13b0f4ac0..a6e73cd588 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -578,7 +578,7 @@ void CWallet::AddToSpends(const uint256& wtxid)
 {
     auto it = mapWallet.find(wtxid);
     assert(it != mapWallet.end());
-    CWalletTx& thisTx = it->second;
+    const CWalletTx& thisTx = it->second;
     if (thisTx.IsCoinBase()) // Coinbases don't spend anything!
         return;
 
@@ -1062,7 +1062,7 @@ bool CWallet::AbandonTransaction(const uint256& hashTx)
     // Can't mark abandoned if confirmed or in mempool
     auto it = mapWallet.find(hashTx);
     assert(it != mapWallet.end());
-    CWalletTx& origtx = it->second;
+    const CWalletTx& origtx = it->second;
     if (origtx.GetDepthInMainChain() != 0 || origtx.InMempool()) {
         return false;
     }
@@ -3077,7 +3077,7 @@ static uint32_t GetLocktimeForNewTransaction(interfaces::Chain& chain, const uin
     return locktime;
 }
 
-OutputType CWallet::TransactionChangeType(const Optional<OutputType>& change_type, const std::vector<CRecipient>& vecSend)
+OutputType CWallet::TransactionChangeType(const Optional<OutputType>& change_type, const std::vector<CRecipient>& vecSend) const
 {
     // If -changetype is specified, always use that change type.
     if (change_type) {
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 6ad993259b..b3f6b4fec1 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -1051,7 +1051,7 @@ public:
     Balance GetBalance(int min_depth = 0, bool avoid_reuse = true) const;
     CAmountMap GetAvailableBalance(const CCoinControl* coinControl = nullptr) const;
 
-    OutputType TransactionChangeType(const Optional<OutputType>& change_type, const std::vector<CRecipient>& vecSend);
+    OutputType TransactionChangeType(const Optional<OutputType>& change_type, const std::vector<CRecipient>& vecSend) const;
 
     /**
      * Insert additional inputs into the transaction by