diff --git a/src/Makefile.am b/src/Makefile.am
index 5485127e68..6d0e1ed7b8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -119,6 +119,7 @@ BITCOIN_CORE_H = \
   txmempool.h \
   ui_interface.h \
   uint256.h \
+  undo.h \
   util.h \
   utilstrencodings.h \
   utilmoneystr.h \
diff --git a/src/coins.h b/src/coins.h
index eafe3bec64..295b3d70d1 100644
--- a/src/coins.h
+++ b/src/coins.h
@@ -10,6 +10,7 @@
 #include "core/transaction.h"
 #include "serialize.h"
 #include "uint256.h"
+#include "undo.h"
 
 #include <assert.h>
 #include <stdint.h>
diff --git a/src/core.h b/src/core.h
index ad4c883250..aeae9a1911 100644
--- a/src/core.h
+++ b/src/core.h
@@ -40,65 +40,6 @@ public:
     }
 };
 
-/** Undo information for a CTxIn
- *
- *  Contains the prevout's CTxOut being spent, and if this was the
- *  last output of the affected transaction, its metadata as well
- *  (coinbase or not, height, transaction version)
- */
-class CTxInUndo
-{
-public:
-    CTxOut txout;         // the txout data before being spent
-    bool fCoinBase;       // if the outpoint was the last unspent: whether it belonged to a coinbase
-    unsigned int nHeight; // if the outpoint was the last unspent: its height
-    int nVersion;         // if the outpoint was the last unspent: its version
-
-    CTxInUndo() : txout(), fCoinBase(false), nHeight(0), nVersion(0) {}
-    CTxInUndo(const CTxOut &txoutIn, bool fCoinBaseIn = false, unsigned int nHeightIn = 0, int nVersionIn = 0) : txout(txoutIn), fCoinBase(fCoinBaseIn), nHeight(nHeightIn), nVersion(nVersionIn) { }
-
-    unsigned int GetSerializeSize(int nType, int nVersion) const {
-        return ::GetSerializeSize(VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion) +
-               (nHeight > 0 ? ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion) : 0) +
-               ::GetSerializeSize(CTxOutCompressor(REF(txout)), nType, nVersion);
-    }
-
-    template<typename Stream>
-    void Serialize(Stream &s, int nType, int nVersion) const {
-        ::Serialize(s, VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion);
-        if (nHeight > 0)
-            ::Serialize(s, VARINT(this->nVersion), nType, nVersion);
-        ::Serialize(s, CTxOutCompressor(REF(txout)), nType, nVersion);
-    }
-
-    template<typename Stream>
-    void Unserialize(Stream &s, int nType, int nVersion) {
-        unsigned int nCode = 0;
-        ::Unserialize(s, VARINT(nCode), nType, nVersion);
-        nHeight = nCode / 2;
-        fCoinBase = nCode & 1;
-        if (nHeight > 0)
-            ::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
-        ::Unserialize(s, REF(CTxOutCompressor(REF(txout))), nType, nVersion);
-    }
-};
-
-/** Undo information for a CTransaction */
-class CTxUndo
-{
-public:
-    // undo information for all txins
-    std::vector<CTxInUndo> vprevout;
-
-    ADD_SERIALIZE_METHODS;
-
-    template <typename Stream, typename Operation>
-    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
-        READWRITE(vprevout);
-    }
-};
-
-
 /** Nodes collect new transactions into a block, hash them into a hash tree,
  * and scan through nonce values to make the block's hash satisfy proof-of-work
  * requirements.  When they solve the proof-of-work, they broadcast the block
diff --git a/src/main.h b/src/main.h
index 3a3687ec1d..09f22471d6 100644
--- a/src/main.h
+++ b/src/main.h
@@ -25,6 +25,7 @@
 #include "tinyformat.h"
 #include "txmempool.h"
 #include "uint256.h"
+#include "undo.h"
 
 #include <algorithm>
 #include <exception>
@@ -129,7 +130,6 @@ static const uint64_t nMinDiskSpace = 52428800;
 
 
 class CBlockTreeDB;
-class CTxUndo;
 class CScriptCheck;
 class CValidationState;
 class CValidationInterface;
diff --git a/src/undo.h b/src/undo.h
new file mode 100644
index 0000000000..78e37f628c
--- /dev/null
+++ b/src/undo.h
@@ -0,0 +1,71 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef H_BITCOIN_TXUNDO
+#define H_BITCOIN_TXUNDO
+
+#include "core.h" // Only for CTxOutCompressor
+#include "core/transaction.h"
+#include "serialize.h"
+
+/** Undo information for a CTxIn
+ *
+ *  Contains the prevout's CTxOut being spent, and if this was the
+ *  last output of the affected transaction, its metadata as well
+ *  (coinbase or not, height, transaction version)
+ */
+class CTxInUndo
+{
+public:
+    CTxOut txout;         // the txout data before being spent
+    bool fCoinBase;       // if the outpoint was the last unspent: whether it belonged to a coinbase
+    unsigned int nHeight; // if the outpoint was the last unspent: its height
+    int nVersion;         // if the outpoint was the last unspent: its version
+
+    CTxInUndo() : txout(), fCoinBase(false), nHeight(0), nVersion(0) {}
+    CTxInUndo(const CTxOut &txoutIn, bool fCoinBaseIn = false, unsigned int nHeightIn = 0, int nVersionIn = 0) : txout(txoutIn), fCoinBase(fCoinBaseIn), nHeight(nHeightIn), nVersion(nVersionIn) { }
+
+    unsigned int GetSerializeSize(int nType, int nVersion) const {
+        return ::GetSerializeSize(VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion) +
+               (nHeight > 0 ? ::GetSerializeSize(VARINT(this->nVersion), nType, nVersion) : 0) +
+               ::GetSerializeSize(CTxOutCompressor(REF(txout)), nType, nVersion);
+    }
+
+    template<typename Stream>
+    void Serialize(Stream &s, int nType, int nVersion) const {
+        ::Serialize(s, VARINT(nHeight*2+(fCoinBase ? 1 : 0)), nType, nVersion);
+        if (nHeight > 0)
+            ::Serialize(s, VARINT(this->nVersion), nType, nVersion);
+        ::Serialize(s, CTxOutCompressor(REF(txout)), nType, nVersion);
+    }
+
+    template<typename Stream>
+    void Unserialize(Stream &s, int nType, int nVersion) {
+        unsigned int nCode = 0;
+        ::Unserialize(s, VARINT(nCode), nType, nVersion);
+        nHeight = nCode / 2;
+        fCoinBase = nCode & 1;
+        if (nHeight > 0)
+            ::Unserialize(s, VARINT(this->nVersion), nType, nVersion);
+        ::Unserialize(s, REF(CTxOutCompressor(REF(txout))), nType, nVersion);
+    }
+};
+
+/** Undo information for a CTransaction */
+class CTxUndo
+{
+public:
+    // undo information for all txins
+    std::vector<CTxInUndo> vprevout;
+
+    ADD_SERIALIZE_METHODS;
+
+    template <typename Stream, typename Operation>
+    inline void SerializationOp(Stream& s, Operation ser_action, int nType, int nVersion) {
+        READWRITE(vprevout);
+    }
+};
+
+#endif // H_BITCOIN_TXUNDO