diff --git a/src/interfaces/handler.cpp b/src/interfaces/handler.cpp
--- a/src/interfaces/handler.cpp
+++ b/src/interfaces/handler.cpp
@@ -15,7 +15,7 @@
 
     class HandlerImpl : public Handler {
     public:
-        HandlerImpl(boost::signals2::connection connection)
+        explicit HandlerImpl(boost::signals2::connection connection)
             : m_connection(std::move(connection)) {}
 
         void disconnect() override { m_connection.disconnect(); }
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -41,7 +41,7 @@
 
     class PendingWalletTxImpl : public PendingWalletTx {
     public:
-        PendingWalletTxImpl(CWallet &wallet)
+        explicit PendingWalletTxImpl(CWallet &wallet)
             : m_wallet(wallet), m_key(&wallet) {}
 
         const CTransaction &get() override { return *m_tx; }
@@ -134,7 +134,7 @@
 
     class WalletImpl : public Wallet {
     public:
-        WalletImpl(const std::shared_ptr<CWallet> &wallet)
+        explicit WalletImpl(const std::shared_ptr<CWallet> &wallet)
             : m_shared_wallet(wallet), m_wallet(*wallet.get()) {}
 
         bool encryptWallet(const SecureString &wallet_passphrase) override {
diff --git a/src/key_io.cpp b/src/key_io.cpp
--- a/src/key_io.cpp
+++ b/src/key_io.cpp
@@ -24,7 +24,8 @@
     const CChainParams &m_params;
 
 public:
-    DestinationEncoder(const CChainParams &params) : m_params(params) {}
+    explicit DestinationEncoder(const CChainParams &params)
+        : m_params(params) {}
 
     std::string operator()(const CKeyID &id) const {
         std::vector<uint8_t> data =
diff --git a/src/qt/addresstablemodel.cpp b/src/qt/addresstablemodel.cpp
--- a/src/qt/addresstablemodel.cpp
+++ b/src/qt/addresstablemodel.cpp
@@ -74,7 +74,7 @@
     QList<AddressTableEntry> cachedAddressTable;
     AddressTableModel *parent;
 
-    AddressTablePriv(AddressTableModel *_parent) : parent(_parent) {}
+    explicit AddressTablePriv(AddressTableModel *_parent) : parent(_parent) {}
 
     void refreshAddressTable(interfaces::Wallet &wallet) {
         cachedAddressTable.clear();
diff --git a/src/qt/rpcconsole.cpp b/src/qt/rpcconsole.cpp
--- a/src/qt/rpcconsole.cpp
+++ b/src/qt/rpcconsole.cpp
@@ -79,7 +79,7 @@
 class RPCExecutor : public QObject {
     Q_OBJECT
 public:
-    RPCExecutor(interfaces::Node &node) : m_node(node) {}
+    explicit RPCExecutor(interfaces::Node &node) : m_node(node) {}
 
 public Q_SLOTS:
     void request(const QString &command, const WalletModel *wallet_model);
diff --git a/src/qt/transactiontablemodel.cpp b/src/qt/transactiontablemodel.cpp
--- a/src/qt/transactiontablemodel.cpp
+++ b/src/qt/transactiontablemodel.cpp
@@ -55,7 +55,8 @@
 // Private implementation
 class TransactionTablePriv {
 public:
-    TransactionTablePriv(TransactionTableModel *_parent) : parent(_parent) {}
+    explicit TransactionTablePriv(TransactionTableModel *_parent)
+        : parent(_parent) {}
 
     TransactionTableModel *parent;
 
diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -33,7 +33,7 @@
 // BOOST_CHECK_EXCEPTION predicates to check the specific validation error
 class HasReason {
 public:
-    HasReason(const std::string &reason) : m_reason(reason) {}
+    explicit HasReason(const std::string &reason) : m_reason(reason) {}
     bool operator()(const std::runtime_error &e) const {
         return std::string(e.what()).find(m_reason) != std::string::npos;
     };
diff --git a/src/test/validation_block_tests.cpp b/src/test/validation_block_tests.cpp
--- a/src/test/validation_block_tests.cpp
+++ b/src/test/validation_block_tests.cpp
@@ -28,7 +28,7 @@
 struct TestSubscriber : public CValidationInterface {
     uint256 m_expected_tip;
 
-    TestSubscriber(uint256 tip) : m_expected_tip(tip) {}
+    explicit TestSubscriber(uint256 tip) : m_expected_tip(tip) {}
 
     void UpdatedBlockTip(const CBlockIndex *pindexNew,
                          const CBlockIndex *pindexFork,