diff --git a/src/qt/recentrequeststablemodel.cpp b/src/qt/recentrequeststablemodel.cpp
index 45934034d..ddc4a563c 100644
--- a/src/qt/recentrequeststablemodel.cpp
+++ b/src/qt/recentrequeststablemodel.cpp
@@ -1,241 +1,243 @@
 // Copyright (c) 2011-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <qt/recentrequeststablemodel.h>
 
 #include <qt/bitcoinunits.h>
 #include <qt/guiutil.h>
 #include <qt/optionsmodel.h>
 #include <qt/walletmodel.h>
 
-#include <algorithm>
 #include <clientversion.h>
 #include <streams.h>
 
+#include <utility>
+
 RecentRequestsTableModel::RecentRequestsTableModel(WalletModel *parent)
     : QAbstractTableModel(parent), walletModel(parent) {
     // Load entries from wallet
     std::vector<std::string> vReceiveRequests;
     parent->loadReceiveRequests(vReceiveRequests);
     for (const std::string &request : vReceiveRequests) {
         addNewRequest(request);
     }
 
     /* These columns must match the indices in the ColumnIndex enumeration */
     columns << tr("Date") << tr("Label") << tr("Message") << getAmountTitle();
 
     connect(walletModel->getOptionsModel(), &OptionsModel::displayUnitChanged,
             this, &RecentRequestsTableModel::updateDisplayUnit);
 }
 
 RecentRequestsTableModel::~RecentRequestsTableModel() {
     /* Intentionally left empty */
 }
 
 int RecentRequestsTableModel::rowCount(const QModelIndex &parent) const {
     Q_UNUSED(parent);
 
     return list.length();
 }
 
 int RecentRequestsTableModel::columnCount(const QModelIndex &parent) const {
     Q_UNUSED(parent);
 
     return columns.length();
 }
 
 QVariant RecentRequestsTableModel::data(const QModelIndex &index,
                                         int role) const {
     if (!index.isValid() || index.row() >= list.length()) {
         return QVariant();
     }
 
     if (role == Qt::DisplayRole || role == Qt::EditRole) {
         const RecentRequestEntry *rec = &list[index.row()];
         switch (index.column()) {
             case Date:
                 return GUIUtil::dateTimeStr(rec->date);
             case Label:
                 if (rec->recipient.label.isEmpty() && role == Qt::DisplayRole) {
                     return tr("(no label)");
                 } else {
                     return rec->recipient.label;
                 }
             case Message:
                 if (rec->recipient.message.isEmpty() &&
                     role == Qt::DisplayRole) {
                     return tr("(no message)");
                 } else {
                     return rec->recipient.message;
                 }
             case Amount:
                 if (rec->recipient.amount == ::Amount::zero() &&
                     role == Qt::DisplayRole) {
                     return tr("(no amount requested)");
                 } else if (role == Qt::EditRole) {
                     return BitcoinUnits::format(
                         walletModel->getOptionsModel()->getDisplayUnit(),
                         rec->recipient.amount, false,
                         BitcoinUnits::separatorNever);
                 } else {
                     return BitcoinUnits::format(
                         walletModel->getOptionsModel()->getDisplayUnit(),
                         rec->recipient.amount);
                 }
         }
     } else if (role == Qt::TextAlignmentRole) {
         if (index.column() == Amount) {
             return (int)(Qt::AlignRight | Qt::AlignVCenter);
         }
     }
     return QVariant();
 }
 
 bool RecentRequestsTableModel::setData(const QModelIndex &index,
                                        const QVariant &value, int role) {
     return true;
 }
 
 QVariant RecentRequestsTableModel::headerData(int section,
                                               Qt::Orientation orientation,
                                               int role) const {
     if (orientation == Qt::Horizontal) {
         if (role == Qt::DisplayRole && section < columns.size()) {
             return columns[section];
         }
     }
     return QVariant();
 }
 
 /** Updates the column title to "Amount (DisplayUnit)" and emits
  * headerDataChanged() signal for table headers to react. */
 void RecentRequestsTableModel::updateAmountColumnTitle() {
     columns[Amount] = getAmountTitle();
     Q_EMIT headerDataChanged(Qt::Horizontal, Amount, Amount);
 }
 
 /** Gets title for amount column including current display unit if optionsModel
  * reference available. */
 QString RecentRequestsTableModel::getAmountTitle() {
     return (this->walletModel->getOptionsModel() != nullptr)
                ? tr("Requested") + " (" +
                      BitcoinUnits::shortName(
                          this->walletModel->getOptionsModel()
                              ->getDisplayUnit()) +
                      ")"
                : "";
 }
 
 QModelIndex RecentRequestsTableModel::index(int row, int column,
                                             const QModelIndex &parent) const {
     Q_UNUSED(parent);
 
     return createIndex(row, column);
 }
 
 bool RecentRequestsTableModel::removeRows(int row, int count,
                                           const QModelIndex &parent) {
     Q_UNUSED(parent);
 
     if (count > 0 && row >= 0 && (row + count) <= list.size()) {
         for (int i = 0; i < count; ++i) {
             const RecentRequestEntry *rec = &list[row + i];
             if (!walletModel->saveReceiveRequest(
                     rec->recipient.address.toStdString(), rec->id, "")) {
                 return false;
             }
         }
 
         beginRemoveRows(parent, row, row + count - 1);
         list.erase(list.begin() + row, list.begin() + row + count);
         endRemoveRows();
         return true;
     } else {
         return false;
     }
 }
 
 Qt::ItemFlags RecentRequestsTableModel::flags(const QModelIndex &index) const {
     return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
 }
 
 // called when adding a request from the GUI
 void RecentRequestsTableModel::addNewRequest(
     const SendCoinsRecipient &recipient) {
     RecentRequestEntry newEntry;
     newEntry.id = ++nReceiveRequestsMaxId;
     newEntry.date = QDateTime::currentDateTime();
     newEntry.recipient = recipient;
 
     CDataStream ss(SER_DISK, CLIENT_VERSION);
     ss << newEntry;
 
     if (!walletModel->saveReceiveRequest(recipient.address.toStdString(),
                                          newEntry.id, ss.str())) {
         return;
     }
 
     addNewRequest(newEntry);
 }
 
 // called from ctor when loading from wallet
 void RecentRequestsTableModel::addNewRequest(const std::string &recipient) {
     std::vector<char> data(recipient.begin(), recipient.end());
     CDataStream ss(data, SER_DISK, CLIENT_VERSION);
 
     RecentRequestEntry entry;
     ss >> entry;
 
     // should not happen
     if (entry.id == 0) {
         return;
     }
 
     if (entry.id > nReceiveRequestsMaxId) {
         nReceiveRequestsMaxId = entry.id;
     }
 
     addNewRequest(entry);
 }
 
 // actually add to table in GUI
 void RecentRequestsTableModel::addNewRequest(RecentRequestEntry &recipient) {
     beginInsertRows(QModelIndex(), 0, 0);
     list.prepend(recipient);
     endInsertRows();
 }
 
 void RecentRequestsTableModel::sort(int column, Qt::SortOrder order) {
     std::sort(list.begin(), list.end(),
               RecentRequestEntryLessThan(column, order));
     Q_EMIT dataChanged(
         index(0, 0, QModelIndex()),
         index(list.size() - 1, NUMBER_OF_COLUMNS - 1, QModelIndex()));
 }
 
 void RecentRequestsTableModel::updateDisplayUnit() {
     updateAmountColumnTitle();
 }
 
-bool RecentRequestEntryLessThan::operator()(RecentRequestEntry &left,
-                                            RecentRequestEntry &right) const {
-    RecentRequestEntry *pLeft = &left;
-    RecentRequestEntry *pRight = &right;
+bool RecentRequestEntryLessThan::
+operator()(const RecentRequestEntry &left,
+           const RecentRequestEntry &right) const {
+    const RecentRequestEntry *pLeft = &left;
+    const RecentRequestEntry *pRight = &right;
     if (order == Qt::DescendingOrder) {
         std::swap(pLeft, pRight);
     }
 
     switch (column) {
         case RecentRequestsTableModel::Date:
             return pLeft->date.toTime_t() < pRight->date.toTime_t();
         case RecentRequestsTableModel::Label:
             return pLeft->recipient.label < pRight->recipient.label;
         case RecentRequestsTableModel::Message:
             return pLeft->recipient.message < pRight->recipient.message;
         case RecentRequestsTableModel::Amount:
             return pLeft->recipient.amount < pRight->recipient.amount;
         default:
             return pLeft->id < pRight->id;
     }
 }
diff --git a/src/qt/recentrequeststablemodel.h b/src/qt/recentrequeststablemodel.h
index c075c519f..8b3008b6b 100644
--- a/src/qt/recentrequeststablemodel.h
+++ b/src/qt/recentrequeststablemodel.h
@@ -1,111 +1,112 @@
 // Copyright (c) 2011-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_QT_RECENTREQUESTSTABLEMODEL_H
 #define BITCOIN_QT_RECENTREQUESTSTABLEMODEL_H
 
 #include <qt/sendcoinsrecipient.h>
 
 #include <QAbstractTableModel>
 #include <QDateTime>
 #include <QStringList>
 
 class WalletModel;
 
 class RecentRequestEntry {
 public:
     RecentRequestEntry()
         : nVersion(RecentRequestEntry::CURRENT_VERSION), id(0) {}
 
     static const int CURRENT_VERSION = 1;
     int nVersion;
     int64_t id;
     QDateTime date;
     SendCoinsRecipient recipient;
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         unsigned int nDate = date.toTime_t();
 
         READWRITE(this->nVersion);
         READWRITE(id);
         READWRITE(nDate);
         READWRITE(recipient);
 
         if (ser_action.ForRead()) date = QDateTime::fromTime_t(nDate);
     }
 };
 
 class RecentRequestEntryLessThan {
 public:
     RecentRequestEntryLessThan(int nColumn, Qt::SortOrder fOrder)
         : column(nColumn), order(fOrder) {}
-    bool operator()(RecentRequestEntry &left, RecentRequestEntry &right) const;
+    bool operator()(const RecentRequestEntry &left,
+                    const RecentRequestEntry &right) const;
 
 private:
     int column;
     Qt::SortOrder order;
 };
 
 /**
  * Model for list of recently generated payment requests / bitcoincash: URIs.
  * Part of wallet model.
  */
 class RecentRequestsTableModel : public QAbstractTableModel {
     Q_OBJECT
 
 public:
     explicit RecentRequestsTableModel(WalletModel *parent);
     ~RecentRequestsTableModel();
 
     enum ColumnIndex {
         Date = 0,
         Label = 1,
         Message = 2,
         Amount = 3,
         NUMBER_OF_COLUMNS
     };
 
     /** @name Methods overridden from QAbstractTableModel
         @{*/
     int rowCount(const QModelIndex &parent) const override;
     int columnCount(const QModelIndex &parent) const override;
     QVariant data(const QModelIndex &index, int role) const override;
     bool setData(const QModelIndex &index, const QVariant &value,
                  int role) override;
     QVariant headerData(int section, Qt::Orientation orientation,
                         int role) const override;
     QModelIndex index(int row, int column,
                       const QModelIndex &parent = QModelIndex()) const override;
     bool removeRows(int row, int count,
                     const QModelIndex &parent = QModelIndex()) override;
     Qt::ItemFlags flags(const QModelIndex &index) const override;
     /*@}*/
 
     const RecentRequestEntry &entry(int row) const { return list[row]; }
     void addNewRequest(const SendCoinsRecipient &recipient);
     void addNewRequest(const std::string &recipient);
     void addNewRequest(RecentRequestEntry &recipient);
 
 public Q_SLOTS:
     void sort(int column, Qt::SortOrder order = Qt::AscendingOrder) override;
     void updateDisplayUnit();
 
 private:
     WalletModel *walletModel;
     QStringList columns;
     QList<RecentRequestEntry> list;
     int64_t nReceiveRequestsMaxId{0};
 
     /** Updates the column title to "Amount (DisplayUnit)" and emits
      * headerDataChanged() signal for table headers to react. */
     void updateAmountColumnTitle();
     /** Gets title for amount column including current display unit if
      * optionsModel reference available. */
     QString getAmountTitle();
 };
 
 #endif // BITCOIN_QT_RECENTREQUESTSTABLEMODEL_H