diff --git a/src/rpc/index_util.cpp b/src/rpc/index_util.cpp
index 4b8bf64a61..fd04ef0231 100644
--- a/src/rpc/index_util.cpp
+++ b/src/rpc/index_util.cpp
@@ -9,8 +9,9 @@
 #include <uint256.h>
 #include <validation.h>
 
-bool GetAddressIndex(uint160 addressHash, AddressType type,
-                     std::vector<std::pair<CAddressIndexKey, CAmount>>& addressIndex, int32_t start, int32_t end)
+bool GetAddressIndex(const uint160& addressHash, const AddressType type,
+                     std::vector<std::pair<CAddressIndexKey, CAmount>>& addressIndex,
+                     const int32_t start, const int32_t end)
 {
     if (!fAddressIndex)
         return error("address index not enabled");
@@ -21,7 +22,7 @@ bool GetAddressIndex(uint160 addressHash, AddressType type,
     return true;
 }
 
-bool GetAddressUnspentIndex(uint160 addressHash, AddressType type,
+bool GetAddressUnspentIndex(const uint160& addressHash, const AddressType type,
                             std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>& unspentOutputs)
 {
     if (!fAddressIndex)
@@ -33,7 +34,7 @@ bool GetAddressUnspentIndex(uint160 addressHash, AddressType type,
     return true;
 }
 
-bool GetSpentIndex(const CTxMemPool& mempool, CSpentIndexKey& key, CSpentIndexValue& value)
+bool GetSpentIndex(const CTxMemPool& mempool, const CSpentIndexKey& key, CSpentIndexValue& value)
 {
     if (!fSpentIndex)
         return false;
diff --git a/src/rpc/index_util.h b/src/rpc/index_util.h
index 15b82eb2a5..adf260b05c 100644
--- a/src/rpc/index_util.h
+++ b/src/rpc/index_util.h
@@ -22,12 +22,12 @@ struct CSpentIndexValue;
 
 enum class AddressType : uint8_t;
 
-bool GetAddressIndex(uint160 addressHash, AddressType type,
+bool GetAddressIndex(const uint160& addressHash, const AddressType type,
                      std::vector<std::pair<CAddressIndexKey, CAmount>>& addressIndex,
-                     int32_t start = 0, int32_t end = 0);
-bool GetAddressUnspentIndex(uint160 addressHash, AddressType type,
+                     const int32_t start = 0, const int32_t end = 0);
+bool GetAddressUnspentIndex(const uint160& addressHash, const AddressType type,
                             std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>& unspentOutputs);
-bool GetSpentIndex(const CTxMemPool& mempool, CSpentIndexKey& key, CSpentIndexValue& value);
+bool GetSpentIndex(const CTxMemPool& mempool, const CSpentIndexKey& key, CSpentIndexValue& value);
 bool GetTimestampIndex(const uint32_t high, const uint32_t low, std::vector<uint256>& hashes);
 
 #endif // BITCOIN_RPC_CLIENT_H
diff --git a/src/txdb.cpp b/src/txdb.cpp
index 9018be6849..f464ca300e 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -263,13 +263,13 @@ bool CBlockTreeDB::WriteBatchSync(const std::vector<std::pair<int, const CBlockF
     return WriteBatch(batch, true);
 }
 
-bool CBlockTreeDB::ReadSpentIndex(CSpentIndexKey &key, CSpentIndexValue &value) {
+bool CBlockTreeDB::ReadSpentIndex(const CSpentIndexKey key, CSpentIndexValue& value) {
     return Read(std::make_pair(DB_SPENTINDEX, key), value);
 }
 
-bool CBlockTreeDB::UpdateSpentIndex(const std::vector<std::pair<CSpentIndexKey, CSpentIndexValue> >&vect) {
+bool CBlockTreeDB::UpdateSpentIndex(const std::vector<std::pair<CSpentIndexKey, CSpentIndexValue>>& vect) {
     CDBBatch batch(*this);
-    for (std::vector<std::pair<CSpentIndexKey,CSpentIndexValue> >::const_iterator it=vect.begin(); it!=vect.end(); it++) {
+    for (std::vector<std::pair<CSpentIndexKey,CSpentIndexValue>>::const_iterator it=vect.begin(); it!=vect.end(); it++) {
         if (it->second.IsNull()) {
             batch.Erase(std::make_pair(DB_SPENTINDEX, it->first));
         } else {
@@ -279,9 +279,9 @@ bool CBlockTreeDB::UpdateSpentIndex(const std::vector<std::pair<CSpentIndexKey,
     return WriteBatch(batch);
 }
 
-bool CBlockTreeDB::UpdateAddressUnspentIndex(const std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue > >&vect) {
+bool CBlockTreeDB::UpdateAddressUnspentIndex(const std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>& vect) {
     CDBBatch batch(*this);
-    for (std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> >::const_iterator it=vect.begin(); it!=vect.end(); it++) {
+    for (std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>::const_iterator it=vect.begin(); it!=vect.end(); it++) {
         if (it->second.IsNull()) {
             batch.Erase(std::make_pair(DB_ADDRESSUNSPENTINDEX, it->first));
         } else {
@@ -291,9 +291,9 @@ bool CBlockTreeDB::UpdateAddressUnspentIndex(const std::vector<std::pair<CAddres
     return WriteBatch(batch);
 }
 
-bool CBlockTreeDB::ReadAddressUnspentIndex(uint160 addressHash, AddressType type,
-                                           std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > &unspentOutputs) {
-
+bool CBlockTreeDB::ReadAddressUnspentIndex(const uint160& addressHash, const AddressType type,
+                                           std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>& unspentOutputs)
+{
     std::unique_ptr<CDBIterator> pcursor(NewIterator());
 
     pcursor->Seek(std::make_pair(DB_ADDRESSUNSPENTINDEX, CAddressIndexIteratorKey(type, addressHash)));
@@ -316,24 +316,24 @@ bool CBlockTreeDB::ReadAddressUnspentIndex(uint160 addressHash, AddressType type
     return true;
 }
 
-bool CBlockTreeDB::WriteAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount > >&vect) {
+bool CBlockTreeDB::WriteAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount>>& vect) {
     CDBBatch batch(*this);
-    for (std::vector<std::pair<CAddressIndexKey, CAmount> >::const_iterator it=vect.begin(); it!=vect.end(); it++)
+    for (std::vector<std::pair<CAddressIndexKey, CAmount>>::const_iterator it=vect.begin(); it!=vect.end(); it++)
         batch.Write(std::make_pair(DB_ADDRESSINDEX, it->first), it->second);
     return WriteBatch(batch);
 }
 
-bool CBlockTreeDB::EraseAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount > >&vect) {
+bool CBlockTreeDB::EraseAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount>>& vect) {
     CDBBatch batch(*this);
-    for (std::vector<std::pair<CAddressIndexKey, CAmount> >::const_iterator it=vect.begin(); it!=vect.end(); it++)
+    for (std::vector<std::pair<CAddressIndexKey, CAmount>>::const_iterator it=vect.begin(); it!=vect.end(); it++)
         batch.Erase(std::make_pair(DB_ADDRESSINDEX, it->first));
     return WriteBatch(batch);
 }
 
-bool CBlockTreeDB::ReadAddressIndex(uint160 addressHash, AddressType type,
-                                    std::vector<std::pair<CAddressIndexKey, CAmount> > &addressIndex,
-                                    int start, int end) {
-
+bool CBlockTreeDB::ReadAddressIndex(const uint160& addressHash, const AddressType type,
+                                    std::vector<std::pair<CAddressIndexKey, CAmount>>& addressIndex,
+                                    const int32_t start, const int32_t end)
+{
     std::unique_ptr<CDBIterator> pcursor(NewIterator());
 
     if (start > 0 && end > 0) {
@@ -363,7 +363,7 @@ bool CBlockTreeDB::ReadAddressIndex(uint160 addressHash, AddressType type,
     return true;
 }
 
-bool CBlockTreeDB::WriteTimestampIndex(const CTimestampIndexKey &timestampIndex) {
+bool CBlockTreeDB::WriteTimestampIndex(const CTimestampIndexKey& timestampIndex) {
     CDBBatch batch(*this);
     batch.Write(std::make_pair(DB_TIMESTAMPINDEX, timestampIndex), 0);
     return WriteBatch(batch);
@@ -376,8 +376,7 @@ bool CBlockTreeDB::EraseTimestampIndex(const CTimestampIndexKey& timestampIndex)
     return WriteBatch(batch);
 }
 
-bool CBlockTreeDB::ReadTimestampIndex(const unsigned int &high, const unsigned int &low, std::vector<uint256> &hashes) {
-
+bool CBlockTreeDB::ReadTimestampIndex(const uint32_t high, const uint32_t low, std::vector<uint256>& hashes) {
     std::unique_ptr<CDBIterator> pcursor(NewIterator());
 
     pcursor->Seek(std::make_pair(DB_TIMESTAMPINDEX, CTimestampIndexIteratorKey(low)));
diff --git a/src/txdb.h b/src/txdb.h
index c2627aa079..b267617400 100644
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -84,19 +84,24 @@ public:
     bool ReadLastBlockFile(int &nFile);
     bool WriteReindexing(bool fReindexing);
     void ReadReindexing(bool &fReindexing);
-    bool ReadSpentIndex(CSpentIndexKey &key, CSpentIndexValue &value);
-    bool UpdateSpentIndex(const std::vector<std::pair<CSpentIndexKey, CSpentIndexValue> >&vect);
-    bool UpdateAddressUnspentIndex(const std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue > >&vect);
-    bool ReadAddressUnspentIndex(uint160 addressHash, AddressType type,
-                                 std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > &vect);
-    bool WriteAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount> > &vect);
-    bool EraseAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount> > &vect);
-    bool ReadAddressIndex(uint160 addressHash, AddressType type,
-                          std::vector<std::pair<CAddressIndexKey, CAmount> > &addressIndex,
-                          int start = 0, int end = 0);
-    bool WriteTimestampIndex(const CTimestampIndexKey &timestampIndex);
+
+    bool ReadSpentIndex(const CSpentIndexKey key, CSpentIndexValue& value);
+    bool UpdateSpentIndex(const std::vector<std::pair<CSpentIndexKey, CSpentIndexValue>>& vect);
+
+    bool ReadAddressUnspentIndex(const uint160& addressHash, const AddressType type,
+                                 std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>& vect);
+    bool UpdateAddressUnspentIndex(const std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue>>& vect);
+
+    bool WriteAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount>>& vect);
+    bool EraseAddressIndex(const std::vector<std::pair<CAddressIndexKey, CAmount>>& vect);
+    bool ReadAddressIndex(const uint160& addressHash, const AddressType type,
+                          std::vector<std::pair<CAddressIndexKey, CAmount>>& addressIndex,
+                          const int32_t start = 0, const int32_t end = 0);
+
+    bool WriteTimestampIndex(const CTimestampIndexKey& timestampIndex);
     bool EraseTimestampIndex(const CTimestampIndexKey& timestampIndex);
-    bool ReadTimestampIndex(const unsigned int &high, const unsigned int &low, std::vector<uint256> &vect);
+    bool ReadTimestampIndex(const uint32_t high, const uint32_t low, std::vector<uint256>& hashes);
+
     bool WriteFlag(const std::string &name, bool fValue);
     bool ReadFlag(const std::string &name, bool &fValue);
     bool LoadBlockIndexGuts(const Consensus::Params& consensusParams, std::function<CBlockIndex*(const uint256&)> insertBlockIndex);