diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 00b1fb38f81..f60809e1968 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -862,9 +862,9 @@ void CTxMemPool::ApplyDelta(const uint256& hash, CAmount &nFeeDelta) const
     nFeeDelta += delta;
 }
 
-void CTxMemPool::ClearPrioritisation(const uint256 hash)
+void CTxMemPool::ClearPrioritisation(const uint256& hash)
 {
-    LOCK(cs);
+    AssertLockHeld(cs);
     mapDeltas.erase(hash);
 }
 
diff --git a/src/txmempool.h b/src/txmempool.h
index 46bcf85712f..ddd87d2eb35 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -627,7 +627,7 @@ public:
     /** Affect CreateNewBlock prioritisation of transactions */
     void PrioritiseTransaction(const uint256& hash, const CAmount& nFeeDelta);
     void ApplyDelta(const uint256& hash, CAmount &nFeeDelta) const EXCLUSIVE_LOCKS_REQUIRED(cs);
-    void ClearPrioritisation(const uint256 hash);
+    void ClearPrioritisation(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Get the transaction in the pool that spends the same prevout */
     const CTransaction* GetConflictTx(const COutPoint& prevout) const EXCLUSIVE_LOCKS_REQUIRED(cs);