diff --git a/src/txmempool.h b/src/txmempool.h
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -596,7 +596,7 @@
         MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
     void removeForReorg(const Config &config, 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);
 
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -611,7 +611,7 @@
 
 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()) {