diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1849,11 +1849,12 @@
 
     {
         LOCK(cs_main);
-        if (mapBlockIndex.count(hash) == 0) {
+
+        CBlockIndex *pblockindex = LookupBlockIndex(hash);
+        if (!pblockindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
 
-        CBlockIndex *pblockindex = mapBlockIndex[hash];
         UnparkBlockAndChildren(pblockindex);
     }