diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -222,9 +222,9 @@
     // actually immutable; deserialization and assignment are implemented,
     // and bypass the constness. This is safe, as they update the entire
     // structure, including the hash.
-    const int32_t nVersion;
     const std::vector<CTxIn> vin;
     const std::vector<CTxOut> vout;
+    const int32_t nVersion;
     const uint32_t nLockTime;
 
 private:
@@ -292,15 +292,16 @@
 
     std::string ToString() const;
 };
+static_assert(sizeof(CTransaction) == 88);
 
 /**
  * A mutable version of CTransaction.
  */
 class CMutableTransaction {
 public:
-    int32_t nVersion;
     std::vector<CTxIn> vin;
     std::vector<CTxOut> vout;
+    int32_t nVersion;
     uint32_t nLockTime;
 
     CMutableTransaction();
@@ -332,6 +333,7 @@
         return a.GetId() == b.GetId();
     }
 };
+static_assert(sizeof(CMutableTransaction) == 56);
 
 typedef std::shared_ptr<const CTransaction> CTransactionRef;
 static inline CTransactionRef MakeTransactionRef() {
diff --git a/src/primitives/transaction.cpp b/src/primitives/transaction.cpp
--- a/src/primitives/transaction.cpp
+++ b/src/primitives/transaction.cpp
@@ -38,7 +38,7 @@
 CMutableTransaction::CMutableTransaction()
     : nVersion(CTransaction::CURRENT_VERSION), nLockTime(0) {}
 CMutableTransaction::CMutableTransaction(const CTransaction &tx)
-    : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout),
+    : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion),
       nLockTime(tx.nLockTime) {}
 
 static uint256 ComputeCMutableTransactionHash(const CMutableTransaction &tx) {
@@ -62,13 +62,13 @@
  * TODO: remove the need for this default constructor entirely.
  */
 CTransaction::CTransaction()
-    : nVersion(CTransaction::CURRENT_VERSION), vin(), vout(), nLockTime(0),
+    : vin(), vout(), nVersion(CTransaction::CURRENT_VERSION), nLockTime(0),
       hash() {}
 CTransaction::CTransaction(const CMutableTransaction &tx)
-    : nVersion(tx.nVersion), vin(tx.vin), vout(tx.vout),
+    : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion),
       nLockTime(tx.nLockTime), hash(ComputeHash()) {}
 CTransaction::CTransaction(CMutableTransaction &&tx)
-    : nVersion(tx.nVersion), vin(std::move(tx.vin)), vout(std::move(tx.vout)),
+    : vin(std::move(tx.vin)), vout(std::move(tx.vout)), nVersion(tx.nVersion),
       nLockTime(tx.nLockTime), hash(ComputeHash()) {}
 
 Amount CTransaction::GetValueOut() const {