diff --git a/src/amount.h b/src/amount.h
--- a/src/amount.h
+++ b/src/amount.h
@@ -18,14 +18,14 @@
     int64_t amount;
 
 public:
-    Amount() : amount(0) {}
+    constexpr Amount() : amount(0) {}
 
-    template <typename T> Amount(T _camount) : amount(_camount) {
+    template <typename T> constexpr Amount(T _camount) : amount(_camount) {
         static_assert(std::is_integral<T>(),
                       "Only integer types can be used as amounts");
     }
 
-    Amount(const Amount &_camount) : amount(_camount.amount) {}
+    constexpr Amount(const Amount &_camount) : amount(_camount.amount) {}
 
     // Allow access to underlying value for non-monetary operations
     int64_t GetSatoshis() const { return amount; }
@@ -41,44 +41,48 @@
         amount -= a.amount;
         return *this;
     }
-    friend bool operator<(const Amount a, const Amount b) {
+    friend constexpr bool operator<(const Amount a, const Amount b) {
         return a.amount < b.amount;
     }
-    friend bool operator==(const Amount a, const Amount b) {
+    friend constexpr bool operator==(const Amount a, const Amount b) {
         return a.amount == b.amount;
     }
-    friend bool operator>(const Amount a, const Amount b) {
+    friend constexpr bool operator>(const Amount a, const Amount b) {
         return b.amount < a.amount;
     }
-    friend bool operator!=(const Amount a, const Amount b) {
+    friend constexpr bool operator!=(const Amount a, const Amount b) {
         return !(a.amount == b.amount);
     }
-    friend bool operator<=(const Amount a, const Amount b) {
+    friend constexpr bool operator<=(const Amount a, const Amount b) {
         return !(a.amount > b.amount);
     }
-    friend bool operator>=(const Amount a, const Amount b) {
+    friend constexpr bool operator>=(const Amount a, const Amount b) {
         return !(a.amount < b.amount);
     }
-    friend Amount operator+(const Amount a, const Amount b) {
+    friend constexpr Amount operator+(const Amount a, const Amount b) {
         return Amount(a.amount + b.amount);
     }
-    friend Amount operator-(const Amount a, const Amount b) {
+    friend constexpr Amount operator-(const Amount a, const Amount b) {
         return Amount(a.amount - b.amount);
     }
     // Implemented for allowing COIN as a base unit.
-    friend Amount operator*(const int64_t a, const Amount b) {
+    friend constexpr Amount operator*(const int64_t a, const Amount b) {
         return Amount(a * b.amount);
     }
-    friend Amount operator*(const int a, const Amount b) {
+    friend constexpr Amount operator*(const int a, const Amount b) {
         return Amount(a * b.amount);
     }
     // DO NOT IMPLEMENT
-    friend Amount operator*(const double a, const Amount b) = delete;
-    int64_t operator/(const Amount b) const { return amount / b.amount; }
-    Amount operator/(const int64_t b) const { return Amount(amount / b); }
-    Amount operator/(const int b) const { return Amount(amount / b); }
+    friend constexpr Amount operator*(const double a, const Amount b) = delete;
+    constexpr int64_t operator/(const Amount b) const {
+        return amount / b.amount;
+    }
+    constexpr Amount operator/(const int64_t b) const {
+        return Amount(amount / b);
+    }
+    constexpr Amount operator/(const int b) const { return Amount(amount / b); }
     // DO NOT IMPLEMENT
-    Amount operator/(const double b) const = delete;
+    constexpr Amount operator/(const double b) const = delete;
 
     // ostream support
     friend std::ostream &operator<<(std::ostream &stream, const Amount &ca) {
diff --git a/src/policy/fees.h b/src/policy/fees.h
--- a/src/policy/fees.h
+++ b/src/policy/fees.h
@@ -198,7 +198,7 @@
 static const double SUFFICIENT_FEETXS = 1;
 
 // Minimum and Maximum values for tracking feerates
-static constexpr double MIN_FEERATE = 10;
+static constexpr Amount MIN_FEERATE(10);
 static const Amount MAX_FEERATE(int64_t(1e7));
 static const Amount INF_FEERATE(MAX_MONEY);
 static const Amount INF_PRIORITY(int64_t(1e9) * MAX_MONEY);
@@ -207,7 +207,7 @@
 // able to give accurate estimates over a large range of potential feerates.
 // Therefore it makes sense to exponentially space the buckets
 /** Spacing of FeeRate buckets */
-static const int64_t FEE_SPACING_FRACTION = 10;
+static const double FEE_SPACING = 1.1;
 
 /**
  * We want to be able to estimate feerates that are needed on tx's to be
diff --git a/src/policy/fees.cpp b/src/policy/fees.cpp
--- a/src/policy/fees.cpp
+++ b/src/policy/fees.cpp
@@ -326,28 +326,28 @@
 // are never double tracked, but it is of no harm to try to remove them again.
 bool CBlockPolicyEstimator::removeTx(uint256 hash) {
     std::map<uint256, TxStatsInfo>::iterator pos = mapMemPoolTxs.find(hash);
-    if (pos != mapMemPoolTxs.end()) {
-        feeStats.removeTx(pos->second.blockHeight, nBestSeenHeight,
-                          pos->second.bucketIndex);
-        mapMemPoolTxs.erase(hash);
-        return true;
-    } else {
+    if (pos == mapMemPoolTxs.end()) {
         return false;
     }
+
+    feeStats.removeTx(pos->second.blockHeight, nBestSeenHeight,
+                      pos->second.bucketIndex);
+    mapMemPoolTxs.erase(hash);
+    return true;
 }
 
 CBlockPolicyEstimator::CBlockPolicyEstimator(const CFeeRate &_minRelayFee)
     : nBestSeenHeight(0), trackedTxs(0), untrackedTxs(0) {
-    static_assert(MIN_FEERATE > 0, "Min feerate must be nonzero");
-    minTrackedFee = _minRelayFee < CFeeRate(Amount(int64_t(MIN_FEERATE)))
-                        ? CFeeRate(Amount(int64_t(MIN_FEERATE)))
-                        : _minRelayFee;
+    static_assert(MIN_FEERATE > Amount(0), "Min feerate must be nonzero");
+    CFeeRate minFeeRate(MIN_FEERATE);
+    minTrackedFee = _minRelayFee < minFeeRate ? minFeeRate : _minRelayFee;
     std::vector<double> vfeelist;
-    for (Amount bucketBoundary = minTrackedFee.GetFeePerK();
-         bucketBoundary <= MAX_FEERATE;
-         bucketBoundary += bucketBoundary / FEE_SPACING_FRACTION) {
-        vfeelist.push_back(double(bucketBoundary.GetSatoshis()));
+    for (double bucketBoundary = minTrackedFee.GetFeePerK().GetSatoshis();
+         bucketBoundary <= double(MAX_FEERATE.GetSatoshis());
+         bucketBoundary *= FEE_SPACING) {
+        vfeelist.push_back(bucketBoundary);
     }
+
     vfeelist.push_back(double(INF_FEERATE.GetSatoshis()));
     feeStats.Initialize(vfeelist, MAX_BLOCK_CONFIRMS, DEFAULT_DECAY);
 }
@@ -562,17 +562,19 @@
     Amount minFeeLimit =
         std::max(Amount(1), minIncrementalFee.GetFeePerK() / 2);
     feeset.insert(Amount(0));
-    for (Amount bucketBoundary = minFeeLimit; bucketBoundary <= MAX_FEERATE;
-         bucketBoundary += bucketBoundary / FEE_SPACING_FRACTION) {
-        feeset.insert(bucketBoundary);
+    for (double bucketBoundary = minFeeLimit.GetSatoshis();
+         bucketBoundary <= double(MAX_FEERATE.GetSatoshis());
+         bucketBoundary *= FEE_SPACING) {
+        feeset.insert(Amount(int64_t(bucketBoundary)));
     }
 }
 
 Amount FeeFilterRounder::round(const Amount currentMinFee) {
-    std::set<Amount>::iterator it = feeset.lower_bound(currentMinFee);
+    auto it = feeset.lower_bound(currentMinFee);
     if ((it != feeset.begin() && insecure_rand.rand32() % 3 != 0) ||
         it == feeset.end()) {
         it--;
     }
+
     return *it;
 }