diff --git a/src/undo.h b/src/undo.h
index 414b78cb7c..d89b98d279 100644
--- a/src/undo.h
+++ b/src/undo.h
@@ -1,145 +1,144 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Copyright (c) 2017 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_UNDO_H
 #define BITCOIN_UNDO_H
 
 #include "coins.h"
 #include "compressor.h"
 #include "consensus/consensus.h"
-#include "primitives/transaction.h"
 #include "serialize.h"
 
 class CBlock;
 class CBlockIndex;
 class CCoinsViewCache;
 class CValidationState;
 
 /**
  * Undo information for a CTxIn
  *
  * Contains the prevout's CTxOut being spent, and its metadata as well (coinbase
  * or not, height). The serialization contains a dummy value of zero. This is be
  * compatible with older versions which expect to see the transaction version
  * there.
  */
 class TxInUndoSerializer {
     const Coin *pcoin;
 
 public:
     TxInUndoSerializer(const Coin *pcoinIn) : pcoin(pcoinIn) {}
 
     template <typename Stream> void Serialize(Stream &s) const {
         ::Serialize(
             s, VARINT(pcoin->GetHeight() * 2 + (pcoin->IsCoinBase() ? 1 : 0)));
         if (pcoin->GetHeight() > 0) {
             // Required to maintain compatibility with older undo format.
             ::Serialize(s, uint8_t(0));
         }
         ::Serialize(s, CTxOutCompressor(REF(pcoin->GetTxOut())));
     }
 };
 
 class TxInUndoDeserializer {
     Coin *pcoin;
 
 public:
     TxInUndoDeserializer(Coin *pcoinIn) : pcoin(pcoinIn) {}
 
     template <typename Stream> void Unserialize(Stream &s) {
         uint32_t nCode = 0;
         ::Unserialize(s, VARINT(nCode));
         uint32_t nHeight = nCode / 2;
         bool fCoinBase = nCode & 1;
         if (nHeight > 0) {
             // Old versions stored the version number for the last spend of a
             // transaction's outputs. Non-final spends were indicated with
             // height = 0.
             int nVersionDummy;
             ::Unserialize(s, VARINT(nVersionDummy));
         }
 
         CTxOut txout;
         ::Unserialize(s, REF(CTxOutCompressor(REF(txout))));
 
         *pcoin = Coin(std::move(txout), nHeight, fCoinBase);
     }
 };
 
 static const size_t MAX_INPUTS_PER_TX =
     MAX_TX_SIZE / ::GetSerializeSize(CTxIn(), SER_NETWORK, PROTOCOL_VERSION);
 
 /** Restore the UTXO in a Coin at a given COutPoint */
 class CTxUndo {
 public:
     // Undo information for all txins
     std::vector<Coin> vprevout;
 
     template <typename Stream> void Serialize(Stream &s) const {
         // TODO: avoid reimplementing vector serializer.
         uint64_t count = vprevout.size();
         ::Serialize(s, COMPACTSIZE(REF(count)));
         for (const auto &prevout : vprevout) {
             ::Serialize(s, REF(TxInUndoSerializer(&prevout)));
         }
     }
 
     template <typename Stream> void Unserialize(Stream &s) {
         // TODO: avoid reimplementing vector deserializer.
         uint64_t count = 0;
         ::Unserialize(s, COMPACTSIZE(count));
         if (count > MAX_INPUTS_PER_TX) {
             throw std::ios_base::failure("Too many input undo records");
         }
         vprevout.resize(count);
         for (auto &prevout : vprevout) {
             ::Unserialize(s, REF(TxInUndoDeserializer(&prevout)));
         }
     }
 };
 
 /** Undo information for a CBlock */
 class CBlockUndo {
 public:
     // For all but the coinbase
     std::vector<CTxUndo> vtxundo;
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         READWRITE(vtxundo);
     }
 };
 
 enum DisconnectResult {
     // All good.
     DISCONNECT_OK,
     // Rolled back, but UTXO set was inconsistent with block.
     DISCONNECT_UNCLEAN,
     // Something else went wrong.
     DISCONNECT_FAILED,
 };
 
 /**
  * Restore the UTXO in a Coin at a given COutPoint.
  * @param undo The Coin to be restored.
  * @param view The coins view to which to apply the changes.
  * @param out The out point that corresponds to the tx input.
  * @return A DisconnectResult
  */
 DisconnectResult UndoCoinSpend(const Coin &undo, CCoinsViewCache &view,
                                const COutPoint &out);
 
 /**
  * Undo a block from the block and the undoblock data.
  * See DisconnectBlock for more details.
  */
 DisconnectResult ApplyBlockUndo(const CBlockUndo &blockUndo,
                                 const CBlock &block, const CBlockIndex *pindex,
                                 CCoinsViewCache &coins);
 
 #endif // BITCOIN_UNDO_H