diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 8090172e3..56f9f34c9 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -542,7 +542,7 @@ void CTxMemPool::removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMem
 void CTxMemPool::removeConflicts(const CTransaction &tx)
 {
     // Remove transactions which depend on inputs of tx, recursively
-    LOCK(cs);
+    AssertLockHeld(cs);
     for (const CTxIn &txin : tx.vin) {
         auto it = mapNextTx.find(txin.prevout);
         if (it != mapNextTx.end()) {
diff --git a/src/txmempool.h b/src/txmempool.h
index ebfcf36e1..784d5453b 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -544,7 +544,7 @@ public:
 
     void removeRecursive(const CTransaction &tx, MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
     void removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags);
-    void removeConflicts(const CTransaction &tx);
+    void removeConflicts(const CTransaction &tx) EXCLUSIVE_LOCKS_REQUIRED(cs);
     void removeForBlock(const std::vector<CTransactionRef>& vtx, unsigned int nBlockHeight);
 
     void clear();