diff --git a/src/chain.h b/src/chain.h
index fbc033281ff..8b03e66a96f 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -164,13 +164,13 @@ public:
     int nHeight{0};
 
     //! Which # file this block is stored in (blk?????.dat)
-    int nFile{0};
+    int nFile GUARDED_BY(::cs_main){0};
 
     //! Byte offset within blk?????.dat where this block's data is stored
-    unsigned int nDataPos{0};
+    unsigned int nDataPos GUARDED_BY(::cs_main){0};
 
     //! Byte offset within rev?????.dat where this block's undo data is stored
-    unsigned int nUndoPos{0};
+    unsigned int nUndoPos GUARDED_BY(::cs_main){0};
 
     //! (memory only) Total amount of work (expected number of hashes) in the chain up to and including this block
     arith_uint256 nChainWork{};
@@ -198,7 +198,7 @@ public:
     //! load to avoid the block index being spuriously rewound.
     //! @sa NeedsRedownload
     //! @sa ActivateSnapshot
-    uint32_t nStatus{0};
+    uint32_t nStatus GUARDED_BY(::cs_main){0};
 
     //! block header
     int32_t nVersion{0};
@@ -382,6 +382,7 @@ public:
 
     SERIALIZE_METHODS(CDiskBlockIndex, obj)
     {
+        LOCK(::cs_main);
         int _nVersion = s.GetVersion();
         if (!(s.GetType() & SER_GETHASH)) READWRITE(VARINT_MODE(_nVersion, VarIntMode::NONNEGATIVE_SIGNED));
 
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 8df0aac2033..c5697983d51 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -818,7 +818,8 @@ static RPCHelpMan getblockfrompeer()
         throw JSONRPCError(RPC_MISC_ERROR, "Block header missing");
     }
 
-    if (index->nStatus & BLOCK_HAVE_DATA) {
+    const bool block_has_data = WITH_LOCK(::cs_main, return index->nStatus & BLOCK_HAVE_DATA);
+    if (block_has_data) {
         throw JSONRPCError(RPC_MISC_ERROR, "Block already downloaded");
     }
 
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index f227fde0f70..e7d9f434f45 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -240,7 +240,8 @@ static RPCHelpMan getrawtransaction()
     if (!tx) {
         std::string errmsg;
         if (blockindex) {
-            if (!(blockindex->nStatus & BLOCK_HAVE_DATA)) {
+            const bool block_has_data = WITH_LOCK(::cs_main, return blockindex->nStatus & BLOCK_HAVE_DATA);
+            if (!block_has_data) {
                 throw JSONRPCError(RPC_MISC_ERROR, "Block not available");
             }
             errmsg = "No such transaction found in the provided block";
diff --git a/src/test/interfaces_tests.cpp b/src/test/interfaces_tests.cpp
index f4bf6ff8c9d..49b7d2003b4 100644
--- a/src/test/interfaces_tests.cpp
+++ b/src/test/interfaces_tests.cpp
@@ -123,6 +123,7 @@ BOOST_AUTO_TEST_CASE(findCommonAncestor)
 
 BOOST_AUTO_TEST_CASE(hasBlocks)
 {
+    LOCK(::cs_main);
     auto& chain = m_node.chain;
     const CChain& active = Assert(m_node.chainman)->ActiveChain();
 
diff --git a/src/txdb.cpp b/src/txdb.cpp
index 85eea888cc5..e2aed1da7c7 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -311,19 +311,23 @@ bool CBlockTreeDB::LoadBlockIndexGuts(const Consensus::Params& consensusParams,
                 CBlockIndex* pindexNew = insertBlockIndex(diskindex.GetBlockHash());
                 pindexNew->pprev          = insertBlockIndex(diskindex.hashPrev);
                 pindexNew->nHeight        = diskindex.nHeight;
-                pindexNew->nFile          = diskindex.nFile;
-                pindexNew->nDataPos       = diskindex.nDataPos;
-                pindexNew->nUndoPos       = diskindex.nUndoPos;
                 pindexNew->nVersion       = diskindex.nVersion;
                 pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
                 pindexNew->nTime          = diskindex.nTime;
                 pindexNew->nBits          = diskindex.nBits;
                 pindexNew->nNonce         = diskindex.nNonce;
-                pindexNew->nStatus        = diskindex.nStatus;
                 pindexNew->nTx            = diskindex.nTx;
+                {
+                    LOCK(::cs_main);
+                    pindexNew->nFile = diskindex.nFile;
+                    pindexNew->nDataPos = diskindex.nDataPos;
+                    pindexNew->nUndoPos = diskindex.nUndoPos;
+                    pindexNew->nStatus = diskindex.nStatus;
+                }
 
-                if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits, consensusParams))
+                if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits, consensusParams)) {
                     return error("%s: CheckProofOfWork failed: %s", __func__, pindexNew->ToString());
+                }
 
                 pcursor->Next();
             } else {