diff --git a/src/ripple/app/ledger/AcceptedLedgerTx.cpp b/src/ripple/app/ledger/AcceptedLedgerTx.cpp
index 61dfc30632..4a8a7a4826 100644
--- a/src/ripple/app/ledger/AcceptedLedgerTx.cpp
+++ b/src/ripple/app/ledger/AcceptedLedgerTx.cpp
@@ -54,7 +54,7 @@ AcceptedLedgerTx::AcceptedLedgerTx (
 
 AcceptedLedgerTx::AcceptedLedgerTx (
     std::shared_ptr<ReadView const> const& ledger,
-    STTx::ref txn,
+    std::shared_ptr<STTx const> const& txn,
     TER result,
     AccountIDCache const& accountCache,
     Logs& logs)
diff --git a/src/ripple/app/ledger/AcceptedLedgerTx.h b/src/ripple/app/ledger/AcceptedLedgerTx.h
index e4552b791d..b3e4c2f9a4 100644
--- a/src/ripple/app/ledger/AcceptedLedgerTx.h
+++ b/src/ripple/app/ledger/AcceptedLedgerTx.h
@@ -62,7 +62,7 @@ public:
         Logs&);
     AcceptedLedgerTx (
         std::shared_ptr<ReadView const> const&,
-        STTx::ref,
+        std::shared_ptr<STTx const> const&,
         TER,
         AccountIDCache const&,
         Logs&);
diff --git a/src/ripple/app/ledger/ConsensusTransSetSF.cpp b/src/ripple/app/ledger/ConsensusTransSetSF.cpp
index 87c8f9fd66..8382fce8fe 100644
--- a/src/ripple/app/ledger/ConsensusTransSetSF.cpp
+++ b/src/ripple/app/ledger/ConsensusTransSetSF.cpp
@@ -57,7 +57,7 @@ void ConsensusTransSetSF::gotNode (
             // skip prefix
             Serializer s (nodeData.data() + 4, nodeData.size() - 4);
             SerialIter sit (s.slice());
-            STTx::pointer stx = std::make_shared<STTx> (std::ref (sit));
+            auto stx = std::make_shared<STTx const> (std::ref (sit));
             assert (stx->getTransactionID () == nodeHash);
             auto const pap = &app_;
             app_.getJobQueue ().addJob (
diff --git a/src/ripple/app/ledger/impl/LedgerConsensusImp.cpp b/src/ripple/app/ledger/impl/LedgerConsensusImp.cpp
index 8f156b9680..65ed57e10a 100644
--- a/src/ripple/app/ledger/impl/LedgerConsensusImp.cpp
+++ b/src/ripple/app/ledger/impl/LedgerConsensusImp.cpp
@@ -1164,7 +1164,7 @@ void LedgerConsensusImp::accept (std::shared_ptr<SHAMap> set)
                     << " not get in";
                 SerialIter sit (it.second->peekTransaction().slice());
 
-                auto txn = std::make_shared<STTx>(sit);
+                auto txn = std::make_shared<STTx const>(sit);
 
                 retriableTxs.insert (txn);
 
diff --git a/src/ripple/app/misc/NetworkOPs.cpp b/src/ripple/app/misc/NetworkOPs.cpp
index 482799efc4..706297a00f 100644
--- a/src/ripple/app/misc/NetworkOPs.cpp
+++ b/src/ripple/app/misc/NetworkOPs.cpp
@@ -155,7 +155,7 @@ public:
     //
 
     // Must complete immediately.
-    void submitTransaction (STTx::pointer) override;
+    void submitTransaction (std::shared_ptr<STTx const> const&) override;
 
     void processTransaction (
         Transaction::pointer& transaction,
@@ -339,7 +339,7 @@ public:
     void pubLedger (Ledger::ref lpAccepted) override;
     void pubProposedTransaction (
         std::shared_ptr<ReadView const> const& lpCurrent,
-        STTx::ref stTxn, TER terResult) override;
+        std::shared_ptr<STTx const> const& stTxn, TER terResult) override;
 
     //--------------------------------------------------------------------------
     //
@@ -639,7 +639,7 @@ std::string NetworkOPsImp::strOperatingMode () const
     return paStatusToken[mMode];
 }
 
-void NetworkOPsImp::submitTransaction (STTx::pointer iTrans)
+void NetworkOPsImp::submitTransaction (std::shared_ptr<STTx const> const& iTrans)
 {
     if (isNeedNetworkLedger ())
     {
@@ -648,11 +648,7 @@ void NetworkOPsImp::submitTransaction (STTx::pointer iTrans)
     }
 
     // this is an asynchronous interface
-    Serializer s;
-    iTrans->add (s);
-
-    SerialIter sit (s.slice());
-    auto trans = std::make_shared<STTx> (std::ref (sit));
+    auto const trans = sterilize(*iTrans);
 
     auto const txid = trans->getTransactionID ();
     auto const flags = app_.getHashRouter().getFlags(txid);
@@ -2005,7 +2001,7 @@ Json::Value NetworkOPsImp::getLedgerFetchInfo ()
 
 void NetworkOPsImp::pubProposedTransaction (
     std::shared_ptr<ReadView const> const& lpCurrent,
-    STTx::ref stTxn, TER terResult)
+    std::shared_ptr<STTx const> const& stTxn, TER terResult)
 {
     Json::Value jvObj   = transJson (*stTxn, terResult, false, lpCurrent);
 
diff --git a/src/ripple/app/misc/NetworkOPs.h b/src/ripple/app/misc/NetworkOPs.h
index 27a422cb8e..ec141bde81 100644
--- a/src/ripple/app/misc/NetworkOPs.h
+++ b/src/ripple/app/misc/NetworkOPs.h
@@ -110,7 +110,7 @@ public:
     //
 
     // must complete immediately
-    virtual void submitTransaction (STTx::pointer) = 0;
+    virtual void submitTransaction (std::shared_ptr<STTx const> const&) = 0;
 
     /**
      * Process transactions as they arrive from the network or which are
@@ -229,7 +229,7 @@ public:
     virtual void pubLedger (Ledger::ref lpAccepted) = 0;
     virtual void pubProposedTransaction (
         std::shared_ptr<ReadView const> const& lpCurrent,
-        STTx::ref stTxn, TER terResult) = 0;
+        std::shared_ptr<STTx const> const& stTxn, TER terResult) = 0;
 };
 
 //------------------------------------------------------------------------------
diff --git a/src/ripple/app/misc/impl/AccountTxPaging.cpp b/src/ripple/app/misc/impl/AccountTxPaging.cpp
index ad0d276f88..82fadaff40 100644
--- a/src/ripple/app/misc/impl/AccountTxPaging.cpp
+++ b/src/ripple/app/misc/impl/AccountTxPaging.cpp
@@ -40,7 +40,7 @@ convertBlobsToTxResult (
     Application& app)
 {
     SerialIter it (makeSlice(rawTxn));
-    STTx::pointer txn = std::make_shared<STTx> (it);
+    auto txn = std::make_shared<STTx const> (it);
     std::string reason;
 
     auto tr = std::make_shared<Transaction> (txn, reason, app);
diff --git a/src/ripple/app/tx/LocalTxs.h b/src/ripple/app/tx/LocalTxs.h
index b8366b7008..4985f8467c 100644
--- a/src/ripple/app/tx/LocalTxs.h
+++ b/src/ripple/app/tx/LocalTxs.h
@@ -36,7 +36,7 @@ public:
     virtual ~LocalTxs () = default;
 
     // Add a new local transaction
-    virtual void push_back (LedgerIndex index, STTx::ref txn) = 0;
+    virtual void push_back (LedgerIndex index, std::shared_ptr<STTx const> const& txn) = 0;
 
     // Return the set of local transactions to a new open ledger
     virtual CanonicalTXSet getTxSet () = 0;
diff --git a/src/ripple/app/tx/Transaction.h b/src/ripple/app/tx/Transaction.h
index 6bba017856..f7ee528048 100644
--- a/src/ripple/app/tx/Transaction.h
+++ b/src/ripple/app/tx/Transaction.h
@@ -64,7 +64,7 @@ public:
 
 public:
     Transaction (
-        STTx::ref, std::string&, Application&) noexcept;
+        std::shared_ptr<STTx const> const&, std::string&, Application&) noexcept;
 
     static
     Transaction::pointer
@@ -90,7 +90,7 @@ public:
     TransStatus
     sqlTransactionStatus(boost::optional<std::string> const& status);
 
-    STTx::ref getSTransaction ()
+    std::shared_ptr<STTx const> const& getSTransaction ()
     {
         return mTransaction;
     }
@@ -170,7 +170,7 @@ private:
     TER             mResult = temUNCERTAIN;
     bool            mApplying = false;
 
-    STTx::pointer   mTransaction;
+    std::shared_ptr<STTx const>   mTransaction;
     Application&    mApp;
     beast::Journal  j_;
 };
diff --git a/src/ripple/app/tx/TransactionMaster.h b/src/ripple/app/tx/TransactionMaster.h
index 8ddb567b80..b257e4e2b7 100644
--- a/src/ripple/app/tx/TransactionMaster.h
+++ b/src/ripple/app/tx/TransactionMaster.h
@@ -37,15 +37,23 @@ public:
     TransactionMaster (TransactionMaster const&) = delete;
     TransactionMaster& operator= (TransactionMaster const&) = delete;
 
-    Transaction::pointer            fetch (uint256 const& , bool checkDisk);
-    STTx::pointer  fetch (std::shared_ptr<SHAMapItem> const& item, SHAMapTreeNode:: TNType type,
-                                           bool checkDisk, std::uint32_t uCommitLedger);
+    Transaction::pointer
+    fetch (uint256 const& , bool checkDisk);
+
+    std::shared_ptr<STTx const>
+    fetch (std::shared_ptr<SHAMapItem> const& item,
+        SHAMapTreeNode:: TNType type,
+            bool checkDisk, std::uint32_t uCommitLedger);
 
     // return value: true = we had the transaction already
     bool inLedger (uint256 const& hash, std::uint32_t ledger);
+
     void canonicalize (Transaction::pointer* pTransaction);
+
     void sweep (void);
-    TaggedCache <uint256, Transaction>& getCache();
+
+    TaggedCache <uint256, Transaction>&
+    getCache();
 
 private:
     Application& mApp;
diff --git a/src/ripple/app/tx/impl/LocalTxs.cpp b/src/ripple/app/tx/impl/LocalTxs.cpp
index 2044345846..a3f1bd343a 100644
--- a/src/ripple/app/tx/impl/LocalTxs.cpp
+++ b/src/ripple/app/tx/impl/LocalTxs.cpp
@@ -59,7 +59,7 @@ public:
     // get into a fully-validated ledger.
     static int const holdLedgers = 5;
 
-    LocalTx (LedgerIndex index, STTx::ref txn)
+    LocalTx (LedgerIndex index, std::shared_ptr<STTx const> const& txn)
         : m_txn (txn)
         , m_expire (index + holdLedgers)
         , m_id (txn->getTransactionID ())
@@ -85,7 +85,7 @@ public:
         return i > m_expire;
     }
 
-    STTx::ref getTX () const
+    std::shared_ptr<STTx const> const& getTX () const
     {
         return m_txn;
     }
@@ -97,7 +97,7 @@ public:
 
 private:
 
-    STTx::pointer m_txn;
+    std::shared_ptr<STTx const> m_txn;
     LedgerIndex                    m_expire;
     uint256                        m_id;
     AccountID                      m_account;
@@ -113,7 +113,7 @@ public:
     LocalTxsImp() = default;
 
     // Add a new transaction to the set of local transactions
-    void push_back (LedgerIndex index, STTx::ref txn) override
+    void push_back (LedgerIndex index, std::shared_ptr<STTx const> const& txn) override
     {
         std::lock_guard <std::mutex> lock (m_lock);
 
diff --git a/src/ripple/app/tx/impl/Transaction.cpp b/src/ripple/app/tx/impl/Transaction.cpp
index 83c79338d4..2d61cad9f8 100644
--- a/src/ripple/app/tx/impl/Transaction.cpp
+++ b/src/ripple/app/tx/impl/Transaction.cpp
@@ -31,7 +31,7 @@
 
 namespace ripple {
 
-Transaction::Transaction (STTx::ref stx,
+Transaction::Transaction (std::shared_ptr<STTx const> const& stx,
     std::string& reason, Application& app)
     noexcept
     : mTransaction (stx)
@@ -62,7 +62,7 @@ Transaction::pointer Transaction::sharedTransaction (
     try
     {
         SerialIter sit (makeSlice(vucTransaction));
-        auto txn = std::make_shared<STTx>(sit);
+        auto txn = std::make_shared<STTx const>(sit);
         std::string reason;
         auto result = std::make_shared<Transaction> (
             txn, reason, app);
@@ -125,7 +125,7 @@ Transaction::pointer Transaction::transactionFromSQL (
         rangeCheckedCast<std::uint32_t>(ledgerSeq.value_or (0));
 
     SerialIter it (makeSlice(rawTxn));
-    auto txn = std::make_shared<STTx> (it);
+    auto txn = std::make_shared<STTx const> (it);
     std::string reason;
     auto tr = std::make_shared<Transaction> (
         txn, reason, app);
diff --git a/src/ripple/app/tx/impl/TransactionMaster.cpp b/src/ripple/app/tx/impl/TransactionMaster.cpp
index 98bd047e02..88b1c9ddac 100644
--- a/src/ripple/app/tx/impl/TransactionMaster.cpp
+++ b/src/ripple/app/tx/impl/TransactionMaster.cpp
@@ -60,11 +60,12 @@ Transaction::pointer TransactionMaster::fetch (uint256 const& txnID, bool checkD
     return txn;
 }
 
-STTx::pointer TransactionMaster::fetch (std::shared_ptr<SHAMapItem> const& item,
+std::shared_ptr<STTx const>
+TransactionMaster::fetch (std::shared_ptr<SHAMapItem> const& item,
         SHAMapTreeNode::TNType type,
         bool checkDisk, std::uint32_t uCommitLedger)
 {
-    STTx::pointer  txn;
+    std::shared_ptr<STTx const>  txn;
     auto iTx = fetch (item->key(), false);
 
     if (!iTx)
@@ -73,12 +74,12 @@ STTx::pointer TransactionMaster::fetch (std::shared_ptr<SHAMapItem> const& item,
         if (type == SHAMapTreeNode::tnTRANSACTION_NM)
         {
             SerialIter sit (item->slice());
-            txn = std::make_shared<STTx> (std::ref (sit));
+            txn = std::make_shared<STTx const> (std::ref (sit));
         }
         else if (type == SHAMapTreeNode::tnTRANSACTION_MD)
         {
             auto blob = SerialIter{item->data(), item->size()}.getVL();
-            txn = std::make_shared<STTx>(SerialIter{blob.data(), blob.size()});
+            txn = std::make_shared<STTx const>(SerialIter{blob.data(), blob.size()});
         }
     }
     else
diff --git a/src/ripple/overlay/impl/PeerImp.cpp b/src/ripple/overlay/impl/PeerImp.cpp
index bf341a8907..3e8849ee90 100644
--- a/src/ripple/overlay/impl/PeerImp.cpp
+++ b/src/ripple/overlay/impl/PeerImp.cpp
@@ -1031,7 +1031,7 @@ PeerImp::onMessage (std::shared_ptr <protocol::TMTransaction> const& m)
 
     try
     {
-        auto stx = std::make_shared<STTx>(sit);
+        auto stx = std::make_shared<STTx const>(sit);
         uint256 txID = stx->getTransactionID ();
 
         int flags;
@@ -1716,7 +1716,7 @@ PeerImp::doFetchPack (const std::shared_ptr<protocol::TMGetObjectByHash>& packet
 
 void
 PeerImp::checkTransaction (int flags,
-    bool checkSignature, STTx::pointer stx)
+    bool checkSignature, std::shared_ptr<STTx const> const& stx)
 {
     // VFALCO TODO Rewrite to not use exceptions
     try
diff --git a/src/ripple/overlay/impl/PeerImp.h b/src/ripple/overlay/impl/PeerImp.h
index 884868e65c..a4d59c89bf 100644
--- a/src/ripple/overlay/impl/PeerImp.h
+++ b/src/ripple/overlay/impl/PeerImp.h
@@ -449,7 +449,8 @@ private:
     doFetchPack (const std::shared_ptr<protocol::TMGetObjectByHash>& packet);
 
     void
-    checkTransaction (int flags, bool checkSignature, STTx::pointer stx);
+    checkTransaction (int flags, bool checkSignature,
+        std::shared_ptr<STTx const> const& stx);
 
     void
     checkPropose (Job& job,
diff --git a/src/ripple/protocol/STTx.h b/src/ripple/protocol/STTx.h
index c8360c62b6..d2fe8b85ec 100644
--- a/src/ripple/protocol/STTx.h
+++ b/src/ripple/protocol/STTx.h
@@ -24,6 +24,7 @@
 #include <ripple/protocol/TxFormats.h>
 #include <boost/container/flat_set.hpp>
 #include <boost/logic/tribool.hpp>
+#include <boost/optional.hpp>
 
 namespace ripple {
 
@@ -42,9 +43,6 @@ class STTx final
 public:
     static char const* getCountedObjectName () { return "STTx"; }
 
-    using pointer = std::shared_ptr<STTx>;
-    using ref     = const std::shared_ptr<STTx>&;
-
     static std::size_t const minMultiSigners = 1;
     static std::size_t const maxMultiSigners = 8;
 
@@ -134,11 +132,22 @@ private:
     bool checkSingleSign () const;
     bool checkMultiSign () const;
 
+    boost::optional<uint256> tid_;
     TxType tx_type_;
 };
 
 bool passesLocalChecks (STObject const& st, std::string&);
 
+/** Sterilize a transaction.
+
+    The transaction is serialized and then deserialized,
+    ensuring that all equivalent transactions are in canonical
+    form. This also ensures that program metadata such as
+    the transaction's digest, are all computed.
+*/
+std::shared_ptr<STTx const>
+sterilize (STTx const& stx);
+
 } // ripple
 
 #endif
diff --git a/src/ripple/protocol/impl/STTx.cpp b/src/ripple/protocol/impl/STTx.cpp
index 42835f755e..f2e0a1c1c7 100644
--- a/src/ripple/protocol/impl/STTx.cpp
+++ b/src/ripple/protocol/impl/STTx.cpp
@@ -27,6 +27,7 @@
 #include <ripple/protocol/STArray.h>
 #include <ripple/protocol/TxFlags.h>
 #include <ripple/protocol/types.h>
+#include <ripple/basics/contract.h>
 #include <ripple/basics/Log.h>
 #include <ripple/basics/StringUtilities.h>
 #include <ripple/json/to_string.h>
@@ -34,6 +35,7 @@
 #include <beast/cxx14/memory.h> // <memory>
 #include <boost/format.hpp>
 #include <array>
+#include <utility>
 
 namespace ripple {
 
@@ -74,6 +76,8 @@ STTx::STTx (STObject&& object)
             "Transaction not legal for format";
         throw std::runtime_error ("transaction not valid");
     }
+
+    tid_ = getHash(HashPrefix::transactionID);
 }
 
 STTx::STTx (SerialIter& sit)
@@ -106,6 +110,8 @@ STTx::STTx (SerialIter& sit)
             "Transaction not legal for format";
         throw std::runtime_error ("transaction not valid");
     }
+
+    tid_ = getHash(HashPrefix::transactionID);
 }
 
 std::string
@@ -161,7 +167,10 @@ STTx::getSigningHash () const
 uint256
 STTx::getTransactionID () const
 {
-    return getHash (HashPrefix::transactionID);
+    assert(tid_);
+    if (! tid_)
+        LogicError("digest is undefined");
+    return *tid_;
 }
 
 Blob STTx::getSignature () const
@@ -180,6 +189,7 @@ void STTx::sign (RippleAddress const& private_key)
 {
     Blob const signature = private_key.accountPrivateSign (getSigningData (*this));
     setFieldVL (sfTxnSignature, signature);
+    tid_ = getHash(HashPrefix::transactionID);
 }
 
 bool STTx::checkSign(bool allowMultiSign) const
@@ -499,4 +509,13 @@ bool passesLocalChecks (STObject const& st, std::string& reason)
     return true;
 }
 
+std::shared_ptr<STTx const>
+sterilize (STTx const& stx)
+{
+    Serializer s;
+    stx.add(s);
+    SerialIter sit(s.slice());
+    return std::make_shared<STTx const>(std::ref(sit));
+}
+
 } // ripple
diff --git a/src/ripple/rpc/handlers/Submit.cpp b/src/ripple/rpc/handlers/Submit.cpp
index c39ebe6c51..18962cbc47 100644
--- a/src/ripple/rpc/handlers/Submit.cpp
+++ b/src/ripple/rpc/handlers/Submit.cpp
@@ -67,11 +67,11 @@ Json::Value doSubmit (RPC::Context& context)
 
     SerialIter sitTrans (makeSlice(ret.first));
 
-    STTx::pointer stpTrans;
+    std::shared_ptr<STTx const> stpTrans;
 
     try
     {
-        stpTrans = std::make_shared<STTx> (std::ref (sitTrans));
+        stpTrans = std::make_shared<STTx const> (std::ref (sitTrans));
     }
     catch (std::exception& e)
     {
diff --git a/src/ripple/rpc/impl/TransactionSign.cpp b/src/ripple/rpc/impl/TransactionSign.cpp
index 4e33d8628b..8d07065fe2 100644
--- a/src/ripple/rpc/impl/TransactionSign.cpp
+++ b/src/ripple/rpc/impl/TransactionSign.cpp
@@ -295,11 +295,11 @@ checkTxJsonFields (
 //------------------------------------------------------------------------------
 
 // A move-only struct that makes it easy to return either a Json::Value or a
-// STTx::pointer from transactionPreProcessImpl ().
+// std::shared_ptr<STTx const> from transactionPreProcessImpl ().
 struct transactionPreProcessResult
 {
     Json::Value const first;
-    STTx::pointer const second;
+    std::shared_ptr<STTx const> const second;
 
     transactionPreProcessResult () = delete;
     transactionPreProcessResult (transactionPreProcessResult const&) = delete;
@@ -318,7 +318,7 @@ struct transactionPreProcessResult
     , second ()
     { }
 
-    transactionPreProcessResult (STTx::pointer&& st)
+    transactionPreProcessResult (std::shared_ptr<STTx const>&& st)
     : first ()
     , second (std::move (st))
     { }
@@ -463,7 +463,7 @@ transactionPreProcessImpl (
         return std::move (err);
     }
 
-    STTx::pointer stpTrans;
+    std::shared_ptr<STTx> stpTrans;
     try
     {
         // If we're generating a multi-signature the SigningPubKey must be
@@ -501,12 +501,12 @@ transactionPreProcessImpl (
         stpTrans->sign (keypair.secretKey);
     }
 
-    return std::move (stpTrans);
+    return transactionPreProcessResult {std::move (stpTrans)};
 }
 
 static
 std::pair <Json::Value, Transaction::pointer>
-transactionConstructImpl (STTx::pointer stpTrans,
+transactionConstructImpl (std::shared_ptr<STTx const> const& stpTrans,
     Rules const& rules, Application& app)
 {
     std::pair <Json::Value, Transaction::pointer> ret;
@@ -931,7 +931,7 @@ Json::Value transactionSubmitMultiSigned (
     }
 
     // Grind through the JSON in tx_json to produce a STTx
-    STTx::pointer stpTrans;
+    std::shared_ptr<STTx> stpTrans;
     {
         STParsedJSONObject parsedTx_json ("tx_json", tx_json);
         if (!parsedTx_json.object)
@@ -944,8 +944,8 @@ Json::Value transactionSubmitMultiSigned (
         }
         try
         {
-            stpTrans =
-                std::make_shared<STTx> (std::move(parsedTx_json.object.get()));
+            stpTrans = std::make_shared<STTx>(
+                std::move(parsedTx_json.object.get()));
         }
         catch (std::exception& ex)
         {
diff --git a/src/ripple/test/jtx/impl/Env.cpp b/src/ripple/test/jtx/impl/Env.cpp
index c4be36dea0..284c60fbdf 100644
--- a/src/ripple/test/jtx/impl/Env.cpp
+++ b/src/ripple/test/jtx/impl/Env.cpp
@@ -270,15 +270,14 @@ void
 Env::submit (JTx const& jt)
 {
     bool didApply;
-    auto const& stx = jt.stx;
-    if (stx)
+    if (jt.stx)
     {
-        txid_ = stx->getTransactionID();
+        txid_ = jt.stx->getTransactionID();
         openLedger.modify(
             [&](OpenView& view, beast::Journal j)
             {
                 std::tie(ter_, didApply) = ripple::apply(
-                    app(), view, *stx, applyFlags(),
+                    app(), view, *jt.stx, applyFlags(),
                         beast::Journal{});
                 return didApply;
             });
@@ -385,8 +384,7 @@ Env::st (JTx const& jt)
 
     try
     {
-        return std::make_shared<STTx>(
-            std::move(*obj));
+        return sterilize(STTx{std::move(*obj)});
     }
     catch(...)
     {