diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1638,15 +1638,15 @@
     const BlockHash hash(uint256S(strHash));
     CValidationState state;
 
+    CBlockIndex *pblockindex;
     {
         LOCK(cs_main);
-        CBlockIndex *pblockindex = LookupBlockIndex(hash);
+        pblockindex = LookupBlockIndex(hash);
         if (!pblockindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
-
-        InvalidateBlock(config, state, pblockindex);
     }
+    InvalidateBlock(config, state, pblockindex);
 
     if (state.IsValid()) {
         ActivateBestChain(config, state);
@@ -1676,15 +1676,16 @@
     const BlockHash hash(uint256S(strHash));
     CValidationState state;
 
+    CBlockIndex *pblockindex;
     {
         LOCK(cs_main);
         if (mapBlockIndex.count(hash) == 0) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
 
-        CBlockIndex *pblockindex = mapBlockIndex[hash];
-        ParkBlock(config, state, pblockindex);
+        pblockindex = mapBlockIndex[hash];
     }
+    ParkBlock(config, state, pblockindex);
 
     if (state.IsValid()) {
         ActivateBestChain(config, state);
diff --git a/src/validation.h b/src/validation.h
--- a/src/validation.h
+++ b/src/validation.h
@@ -644,11 +644,11 @@
 
 /** Mark a block as invalid. */
 bool InvalidateBlock(const Config &config, CValidationState &state,
-                     CBlockIndex *pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+                     CBlockIndex *pindex);
 
 /** Park a block. */
 bool ParkBlock(const Config &config, CValidationState &state,
-               CBlockIndex *pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+               CBlockIndex *pindex);
 
 /** Remove invalidity status from a block and its descendants. */
 void ResetBlockFailureFlags(CBlockIndex *pindex)
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -169,8 +169,7 @@
     bool PreciousBlock(const Config &config, CValidationState &state,
                        CBlockIndex *pindex) LOCKS_EXCLUDED(cs_main);
     bool UnwindBlock(const Config &config, CValidationState &state,
-                     CBlockIndex *pindex, bool invalidate)
-        EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+                     CBlockIndex *pindex, bool invalidate);
     void ResetBlockFailureFlags(CBlockIndex *pindex)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     template <typename F>
@@ -3026,7 +3025,7 @@
 
 bool CChainState::UnwindBlock(const Config &config, CValidationState &state,
                               CBlockIndex *pindex, bool invalidate) {
-    AssertLockHeld(cs_main);
+    LOCK(cs_main);
 
     // We first disconnect backwards and then mark the blocks as invalid.
     // This prevents a case where pruned nodes may fail to invalidateblock