diff --git a/src/chain.h b/src/chain.h
index 240dd6058..068090523 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -184,6 +184,10 @@ class CBlockIndex
     unsigned int nBits;
     uint256 nNonce;
 
+    //! (currently memory only, but don't have to be)
+    bool cache_init;
+    uint256 cache_block_hash, cache_PoW_hash;
+
     //! (memory only) Sequential id assigned to distinguish order in which blocks are received.
     uint32_t nSequenceId;
 
@@ -215,6 +219,8 @@ class CBlockIndex
         nTime          = 0;
         nBits          = 0;
         nNonce         = uint256();
+
+        cache_init     = false;
     }
 
     CBlockIndex()
@@ -232,6 +238,10 @@ class CBlockIndex
         nTime          = block.nTime;
         nBits          = block.nBits;
         nNonce         = block.nNonce;
+
+        cache_init     = block.cache_init;
+        cache_block_hash = block.cache_block_hash;
+        cache_PoW_hash = block.cache_PoW_hash;
     }
 
     CDiskBlockPos GetBlockPos() const {
@@ -263,6 +273,9 @@ class CBlockIndex
         block.nTime          = nTime;
         block.nBits          = nBits;
         block.nNonce         = nNonce;
+        block.cache_init     = cache_init;
+        block.cache_block_hash = cache_block_hash;
+        block.cache_PoW_hash = cache_PoW_hash;
         return block;
     }
 
diff --git a/src/main.cpp b/src/main.cpp
index 14b84065f..43c748393 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,6 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2014 The Bitcoin Core developers
+// Copyright (c) 2018-2019 The Resistance developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -3818,6 +3819,26 @@ static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart, unsigned
 
 bool ProcessNewBlock(CValidationState &state, CNode* pfrom, CBlock* pblock, bool fForceProcessing, CDiskBlockPos *dbp)
 {
+    // Look for this block's header in the index like AcceptBlock() will
+    uint256 hash = pblock->GetHash();
+
+    {
+        LOCK(cs_main);
+
+        BlockMap::iterator miSelf = mapBlockIndex.find(hash);
+        CBlockIndex *pindex = NULL;
+        if (miSelf != mapBlockIndex.end()) {
+            // Block header is already known
+            pindex = miSelf->second;
+            if (!pblock->cache_init && pindex->cache_init) {
+                LOCK(pblock->cache_lock); // Probably unnecessary since no concurrent access to pblock is expected
+                pblock->cache_init = true;
+                pblock->cache_block_hash = pindex->cache_block_hash;
+                pblock->cache_PoW_hash = pindex->cache_PoW_hash;
+            }
+        }
+    }
+
     // Preliminary checks
     auto verifier = libzcash::ProofVerifier::Disabled();
     bool checked = CheckBlock(*pblock, state, verifier);
diff --git a/src/primitives/block.h b/src/primitives/block.h
index a083dcf4b..a39081b1e 100644
--- a/src/primitives/block.h
+++ b/src/primitives/block.h
@@ -81,6 +81,10 @@ class CBlockHeaderUncached
 class CBlockHeader : public CBlockHeaderUncached
 {
 public:
+    mutable CCriticalSection cache_lock;
+    mutable bool cache_init;
+    mutable uint256 cache_block_hash, cache_PoW_hash;
+
     CBlockHeader()
     {
         cache_init = false;
@@ -101,11 +105,6 @@ class CBlockHeader : public CBlockHeaderUncached
     }
 
     uint256 GetPoWHash_cached() const;
-
-private:
-    mutable CCriticalSection cache_lock;
-    mutable bool cache_init;
-    mutable uint256 cache_block_hash, cache_PoW_hash;
 };