diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 65c8b4ea606..9f785d4115d 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -14,6 +14,7 @@
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <reverse_iterator.h>
+#include <util/check.h>
 #include <util/moneystr.h>
 #include <util/system.h>
 #include <util/time.h>
@@ -82,6 +83,7 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& tx, CAmount fee,
       entryHeight{entry_height},
       spendsCoinbase{spends_coinbase},
       sigOpCost{sigops_cost},
+      m_modified_fee{nFee},
       lockPoints{lp},
       nSizeWithDescendants{GetTxSize()},
       nModFeesWithDescendants{nFee},
@@ -89,11 +91,11 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& tx, CAmount fee,
       nModFeesWithAncestors{nFee},
       nSigOpCostWithAncestors{sigOpCost} {}
 
-void CTxMemPoolEntry::UpdateFeeDelta(CAmount newFeeDelta)
+void CTxMemPoolEntry::UpdateModifiedFee(CAmount fee_diff)
 {
-    nModFeesWithDescendants += newFeeDelta - feeDelta;
-    nModFeesWithAncestors += newFeeDelta - feeDelta;
-    feeDelta = newFeeDelta;
+    nModFeesWithDescendants += fee_diff;
+    nModFeesWithAncestors += fee_diff;
+    m_modified_fee += fee_diff;
 }
 
 void CTxMemPoolEntry::UpdateLockPoints(const LockPoints& lp)
@@ -483,8 +485,10 @@ void CTxMemPool::addUnchecked(const CTxMemPoolEntry &entry, setEntries &setAnces
     // Update transaction for any feeDelta created by PrioritiseTransaction
     CAmount delta{0};
     ApplyDelta(entry.GetTx().GetHash(), delta);
+    // The following call to UpdateModifiedFee assumes no previous fee modifications
+    Assume(entry.GetFee() == entry.GetModifiedFee());
     if (delta) {
-        mapTx.modify(newit, [&delta](CTxMemPoolEntry& e) { e.UpdateFeeDelta(delta); });
+        mapTx.modify(newit, [&delta](CTxMemPoolEntry& e) { e.UpdateModifiedFee(delta); });
     }
 
     // Update cachedInnerUsage to include contained transaction's usage.
@@ -920,7 +924,7 @@ void CTxMemPool::PrioritiseTransaction(const uint256& hash, const CAmount& nFeeD
         delta += nFeeDelta;
         txiter it = mapTx.find(hash);
         if (it != mapTx.end()) {
-            mapTx.modify(it, [&delta](CTxMemPoolEntry& e) { e.UpdateFeeDelta(delta); });
+            mapTx.modify(it, [&nFeeDelta](CTxMemPoolEntry& e) { e.UpdateModifiedFee(nFeeDelta); });
             // Now update all ancestors' modified fees with descendants
             setEntries setAncestors;
             uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
diff --git a/src/txmempool.h b/src/txmempool.h
index f5d5abc62e4..6320378c04d 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -101,7 +101,7 @@ private:
     const unsigned int entryHeight; //!< Chain height when entering the mempool
     const bool spendsCoinbase;      //!< keep track of transactions that spend a coinbase
     const int64_t sigOpCost;        //!< Total sigop cost
-    CAmount feeDelta{0};            //!< Used for determining the priority of the transaction for mining in a block
+    CAmount m_modified_fee;         //!< Used for determining the priority of the transaction for mining in a block
     LockPoints lockPoints;     //!< Track the height and time at which tx was final
 
     // Information about descendants of this transaction that are in the
@@ -131,7 +131,7 @@ public:
     std::chrono::seconds GetTime() const { return std::chrono::seconds{nTime}; }
     unsigned int GetHeight() const { return entryHeight; }
     int64_t GetSigOpCost() const { return sigOpCost; }
-    CAmount GetModifiedFee() const { return nFee + feeDelta; }
+    CAmount GetModifiedFee() const { return m_modified_fee; }
     size_t DynamicMemoryUsage() const { return nUsageSize; }
     const LockPoints& GetLockPoints() const { return lockPoints; }
 
@@ -139,9 +139,8 @@ public:
     void UpdateDescendantState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount);
     // Adjusts the ancestor state
     void UpdateAncestorState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount, int64_t modifySigOps);
-    // Updates the fee delta used for mining priority score, and the
-    // modified fees with descendants/ancestors.
-    void UpdateFeeDelta(CAmount newFeeDelta);
+    // Updates the modified fees with descendants/ancestors.
+    void UpdateModifiedFee(CAmount fee_diff);
     // Update the LockPoints after a reorg
     void UpdateLockPoints(const LockPoints& lp);