diff --git a/src/validation.cpp b/src/validation.cpp
index 622a88996a..bf5fa9b011 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3267,10 +3267,7 @@ void CChainState::ReceivedBlockTransactions(const CBlock& block, CBlockIndex* pi
             CBlockIndex *pindex = queue.front();
             queue.pop_front();
             pindex->nChainTx = (pindex->pprev ? pindex->pprev->nChainTx : 0) + pindex->nTx;
-            {
-                LOCK(cs_nBlockSequenceId);
-                pindex->nSequenceId = nBlockSequenceId++;
-            }
+            pindex->nSequenceId = nBlockSequenceId++;
             if (m_chain.Tip() == nullptr || !setBlockIndexCandidates.value_comp()(pindex, m_chain.Tip())) {
                 setBlockIndexCandidates.insert(pindex);
             }
diff --git a/src/validation.h b/src/validation.h
index f62dc9aa61..a3d45337e4 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -558,9 +558,8 @@ protected:
      * Every received block is assigned a unique and increasing identifier, so we
      * know which one to give priority in case of a fork.
      */
-    RecursiveMutex cs_nBlockSequenceId;
     /** Blocks loaded from disk are assigned id 0, so start the counter at 1. */
-    int32_t nBlockSequenceId = 1;
+    int32_t nBlockSequenceId GUARDED_BY(::cs_main) = 1;
     /** Decreasing counter (used by subsequent preciousblock calls). */
     int32_t nBlockReverseSequenceId = -1;
     /** chainwork for the last block that preciousblock has been applied to. */
@@ -750,7 +749,7 @@ public:
 
     void PruneBlockIndexCandidates();
 
-    void UnloadBlockIndex();
+    void UnloadBlockIndex() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
     /** Check whether we are doing an initial block download (synchronizing from disk or network) */
     bool IsInitialBlockDownload() const;