diff --git a/src/chain.cpp b/src/chain.cpp
index d43dc1408..48ac80373 100644
--- a/src/chain.cpp
+++ b/src/chain.cpp
@@ -1,196 +1,202 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chain.h>
 
 /**
  * CChain implementation
  */
 void CChain::SetTip(CBlockIndex *pindex) {
     if (pindex == nullptr) {
         vChain.clear();
         return;
     }
 
     vChain.resize(pindex->nHeight + 1);
     while (pindex && vChain[pindex->nHeight] != pindex) {
         vChain[pindex->nHeight] = pindex;
         pindex = pindex->pprev;
     }
 }
 
 CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const {
     int nStep = 1;
     std::vector<BlockHash> vHave;
     vHave.reserve(32);
 
     if (!pindex) {
         pindex = Tip();
     }
     while (pindex) {
         vHave.push_back(pindex->GetBlockHash());
         // Stop when we have added the genesis block.
         if (pindex->nHeight == 0) {
             break;
         }
         // Exponentially larger steps back, plus the genesis block.
         int nHeight = std::max(pindex->nHeight - nStep, 0);
         if (Contains(pindex)) {
             // Use O(1) CChain index if possible.
             pindex = (*this)[nHeight];
         } else {
             // Otherwise, use O(log n) skiplist.
             pindex = pindex->GetAncestor(nHeight);
         }
         if (vHave.size() > 10) {
             nStep *= 2;
         }
     }
 
     return CBlockLocator(vHave);
 }
 
 const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
     if (pindex == nullptr) {
         return nullptr;
     }
     if (pindex->nHeight > Height()) {
         pindex = pindex->GetAncestor(Height());
     }
     while (pindex && !Contains(pindex)) {
         pindex = pindex->pprev;
     }
     return pindex;
 }
 
 CBlockIndex *CChain::FindEarliestAtLeast(int64_t nTime) const {
     std::vector<CBlockIndex *>::const_iterator lower =
         std::lower_bound(vChain.begin(), vChain.end(), nTime,
                          [](CBlockIndex *pBlock, const int64_t &time) -> bool {
                              return pBlock->GetBlockTimeMax() < time;
                          });
     return (lower == vChain.end() ? nullptr : *lower);
 }
 
 /** Turn the lowest '1' bit in the binary representation of a number into a '0'.
  */
 static inline int InvertLowestOne(int n) {
     return n & (n - 1);
 }
 
 /** Compute what height to jump back to with the CBlockIndex::pskip pointer. */
 static inline int GetSkipHeight(int height) {
     if (height < 2) {
         return 0;
     }
 
     // Determine which height to jump back to. Any number strictly lower than
     // height is acceptable, but the following expression seems to perform well
     // in simulations (max 110 steps to go back up to 2**18 blocks).
     return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1
                         : InvertLowestOne(height);
 }
 
 const CBlockIndex *CBlockIndex::GetAncestor(int height) const {
     if (height > nHeight || height < 0) {
         return nullptr;
     }
 
     const CBlockIndex *pindexWalk = this;
     int heightWalk = nHeight;
     while (heightWalk > height) {
         int heightSkip = GetSkipHeight(heightWalk);
         int heightSkipPrev = GetSkipHeight(heightWalk - 1);
         if (pindexWalk->pskip != nullptr &&
             (heightSkip == height ||
              (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
                                        heightSkipPrev >= height)))) {
             // Only follow pskip if pprev->pskip isn't better than pskip->pprev.
             pindexWalk = pindexWalk->pskip;
             heightWalk = heightSkip;
         } else {
             assert(pindexWalk->pprev);
             pindexWalk = pindexWalk->pprev;
             heightWalk--;
         }
     }
     return pindexWalk;
 }
 
 CBlockIndex *CBlockIndex::GetAncestor(int height) {
     return const_cast<CBlockIndex *>(
         const_cast<const CBlockIndex *>(this)->GetAncestor(height));
 }
 
 void CBlockIndex::BuildSkip() {
     if (pprev) {
         pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
     }
 }
 
 arith_uint256 GetBlockProof(const CBlockIndex &block) {
     arith_uint256 bnTarget;
     bool fNegative;
     bool fOverflow;
     bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);
     if (fNegative || fOverflow || bnTarget == 0) {
         return 0;
     }
     // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256
     // as it's too large for an arith_uint256. However, as 2**256 is at least as
     // large as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) /
     // (bnTarget+1)) + 1, or ~bnTarget / (bnTarget+1) + 1.
     return (~bnTarget / (bnTarget + 1)) + 1;
 }
 
 int64_t GetBlockProofEquivalentTime(const CBlockIndex &to,
                                     const CBlockIndex &from,
                                     const CBlockIndex &tip,
                                     const Consensus::Params &params) {
     arith_uint256 r;
     int sign = 1;
     if (to.nChainWork > from.nChainWork) {
         r = to.nChainWork - from.nChainWork;
     } else {
         r = from.nChainWork - to.nChainWork;
         sign = -1;
     }
     r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);
     if (r.bits() > 63) {
         return sign * std::numeric_limits<int64_t>::max();
     }
     return sign * r.GetLow64();
 }
 
 /**
  * Find the last common ancestor two blocks have.
  * Both pa and pb must be non null.
  */
 const CBlockIndex *LastCommonAncestor(const CBlockIndex *pa,
                                       const CBlockIndex *pb) {
     if (pa->nHeight > pb->nHeight) {
         pa = pa->GetAncestor(pb->nHeight);
     } else if (pb->nHeight > pa->nHeight) {
         pb = pb->GetAncestor(pa->nHeight);
     }
 
     while (pa != pb && pa && pb) {
-        pa = pa->pprev;
-        pb = pb->pprev;
+        if (pa->pskip && pb->pskip && pa->pskip != pb->pskip) {
+            pa = pa->pskip;
+            pb = pb->pskip;
+            assert(pa->nHeight == pb->nHeight);
+        } else {
+            pa = pa->pprev;
+            pb = pb->pprev;
+        }
     }
 
     // Eventually all chain branches meet at the genesis block.
     assert(pa == pb);
     return pa;
 }
 
 bool AreOnTheSameFork(const CBlockIndex *pa, const CBlockIndex *pb) {
     if (pa->nHeight > pb->nHeight) {
         pa = pa->GetAncestor(pb->nHeight);
     } else if (pb->nHeight > pa->nHeight) {
         pb = pb->GetAncestor(pa->nHeight);
     }
     return pa == pb;
 }