diff --git a/src/BtDependency.cc b/src/BtDependency.cc
index 9c9976bf..4e8a9565 100644
--- a/src/BtDependency.cc
+++ b/src/BtDependency.cc
@@ -101,7 +101,7 @@ bool BtDependency::resolve()
       diskAdaptor->openExistingFile();
       std::string content = util::toString(diskAdaptor);
       if(dependee->getDownloadContext()->hasAttribute(CTX_ATTR_BT)) {
-        std::shared_ptr<TorrentAttribute> attrs =
+        auto attrs =
           bittorrent::getTorrentAttrs(dependee->getDownloadContext());
         bittorrent::loadFromMemory
           (bittorrent::metadata2Torrent(content, attrs), context,
diff --git a/src/BtSetup.cc b/src/BtSetup.cc
index 43457d86..b3f446bd 100644
--- a/src/BtSetup.cc
+++ b/src/BtSetup.cc
@@ -98,7 +98,7 @@ void BtSetup::setup(std::vector<Command*>& commands,
   if(!requestGroup->getDownloadContext()->hasAttribute(CTX_ATTR_BT)){
     return;
   }
-  std::shared_ptr<TorrentAttribute> torrentAttrs =
+  auto torrentAttrs =
     bittorrent::getTorrentAttrs(requestGroup->getDownloadContext());
   bool metadataGetMode = torrentAttrs->metadata.empty();
   const std::shared_ptr<BtRegistry>& btReg = e->getBtRegistry();
diff --git a/src/DefaultBtInteractive.cc b/src/DefaultBtInteractive.cc
index 61b8343d..c6c088e9 100644
--- a/src/DefaultBtInteractive.cc
+++ b/src/DefaultBtInteractive.cc
@@ -195,8 +195,7 @@ void DefaultBtInteractive::addHandshakeExtendedMessageToQueue()
   m->setClientVersion("aria2/" PACKAGE_VERSION);
   m->setTCPPort(tcpPort_);
   m->setExtensions(extensionMessageRegistry_->getExtensions());
-  std::shared_ptr<TorrentAttribute> attrs =
-    bittorrent::getTorrentAttrs(downloadContext_);
+  auto attrs = bittorrent::getTorrentAttrs(downloadContext_);
   if(!attrs->metadata.empty()) {
     m->setMetadataSize(attrs->metadataSize);
   }
diff --git a/src/DefaultPieceStorage.cc b/src/DefaultPieceStorage.cc
index 1c400b33..811c68b7 100644
--- a/src/DefaultPieceStorage.cc
+++ b/src/DefaultPieceStorage.cc
@@ -478,8 +478,7 @@ void DefaultPieceStorage::completePiece(const std::shared_ptr<Piece>& piece)
     }
 #ifdef ENABLE_BITTORRENT
     if(downloadContext_->hasAttribute(CTX_ATTR_BT)) {
-      std::shared_ptr<TorrentAttribute> torrentAttrs =
-        bittorrent::getTorrentAttrs(downloadContext_);
+      auto torrentAttrs = bittorrent::getTorrentAttrs(downloadContext_);
       if(!torrentAttrs->metadata.empty()) {
 #ifdef __MINGW32__
         // On Windows, if aria2 opens files with GENERIC_WRITE access
diff --git a/src/DownloadContext.cc b/src/DownloadContext.cc
index 7fba6d55..5620cc5f 100644
--- a/src/DownloadContext.cc
+++ b/src/DownloadContext.cc
@@ -150,19 +150,18 @@ void DownloadContext::setFileFilter(SegList<int>& sgl)
 }
 
 void DownloadContext::setAttribute
-(ContextAttributeType key, const std::shared_ptr<ContextAttribute>& value)
+(ContextAttributeType key, std::unique_ptr<ContextAttribute>&& value)
 {
   assert(key < MAX_CTX_ATTR);
-  attrs_[key] = value;
+  attrs_[key] = std::move(value);
 }
 
-const std::shared_ptr<ContextAttribute>& DownloadContext::getAttribute
-(ContextAttributeType key)
+ContextAttribute* DownloadContext::getAttribute(ContextAttributeType key)
 {
   assert(key < MAX_CTX_ATTR);
-  const std::shared_ptr<ContextAttribute>& attr = attrs_[key];
+  const std::unique_ptr<ContextAttribute>& attr = attrs_[key];
   if(attr) {
-    return attr;
+    return attr.get();
   } else {
     throw DL_ABORT_EX(fmt("No attribute named %s",
                           strContextAttributeType(key)));
diff --git a/src/DownloadContext.h b/src/DownloadContext.h
index ee5df7be..ddac615d 100644
--- a/src/DownloadContext.h
+++ b/src/DownloadContext.h
@@ -78,7 +78,7 @@ private:
 
   RequestGroup* ownerRequestGroup_;
 
-  std::vector<std::shared_ptr<ContextAttribute> > attrs_;
+  std::vector<std::unique_ptr<ContextAttribute> > attrs_;
 
   NetStat netStat_;
 
@@ -204,9 +204,9 @@ public:
   }
 
   void setAttribute
-  (ContextAttributeType key, const std::shared_ptr<ContextAttribute>& value);
+  (ContextAttributeType key, std::unique_ptr<ContextAttribute>&& value);
 
-  const std::shared_ptr<ContextAttribute>& getAttribute(ContextAttributeType key);
+  ContextAttribute* getAttribute(ContextAttributeType key);
 
   bool hasAttribute(ContextAttributeType key) const;
 
diff --git a/src/HandshakeExtensionMessage.cc b/src/HandshakeExtensionMessage.cc
index 1a39e782..f37526f1 100644
--- a/src/HandshakeExtensionMessage.cc
+++ b/src/HandshakeExtensionMessage.cc
@@ -109,7 +109,7 @@ void HandshakeExtensionMessage::doReceivedAction()
       peer_->setExtension(i, id);
     }
   }
-  std::shared_ptr<TorrentAttribute> attrs = bittorrent::getTorrentAttrs(dctx_);
+  auto attrs = bittorrent::getTorrentAttrs(dctx_);
   if(attrs->metadata.empty()) {
     if(!peer_->getExtensionMessageID(ExtensionMessageRegistry::UT_METADATA)) {
       // TODO In metadataGetMode, if peer don't support metadata
diff --git a/src/PeerInteractionCommand.cc b/src/PeerInteractionCommand.cc
index c9e118c3..35b18328 100644
--- a/src/PeerInteractionCommand.cc
+++ b/src/PeerInteractionCommand.cc
@@ -114,7 +114,7 @@ PeerInteractionCommand::PeerInteractionCommand
     family = AF_INET;
   }
 
-  std::shared_ptr<TorrentAttribute> torrentAttrs =
+  auto torrentAttrs =
     bittorrent::getTorrentAttrs(requestGroup_->getDownloadContext());
   bool metadataGetMode = torrentAttrs->metadata.empty();
 
diff --git a/src/RequestGroup.cc b/src/RequestGroup.cc
index 66bc2898..74e028fc 100644
--- a/src/RequestGroup.cc
+++ b/src/RequestGroup.cc
@@ -287,8 +287,7 @@ void RequestGroup::createInitialCommand
 #ifdef ENABLE_BITTORRENT
   {
     if(downloadContext_->hasAttribute(CTX_ATTR_BT)) {
-      std::shared_ptr<TorrentAttribute> torrentAttrs =
-        bittorrent::getTorrentAttrs(downloadContext_);
+      auto torrentAttrs = bittorrent::getTorrentAttrs(downloadContext_);
       bool metadataGetMode = torrentAttrs->metadata.empty();
       if(option_->getAsBool(PREF_DRY_RUN)) {
         throw DOWNLOAD_FAILURE_EXCEPTION
@@ -1207,8 +1206,7 @@ void RequestGroup::reportDownloadFinished()
     int64_t completedLength = getCompletedLength();
     double shareRatio = completedLength == 0 ? 0.0 :
       1.0*stat.allTimeUploadLength/completedLength;
-    std::shared_ptr<TorrentAttribute> attrs =
-      bittorrent::getTorrentAttrs(downloadContext_);
+    auto attrs = bittorrent::getTorrentAttrs(downloadContext_);
     if(!attrs->metadata.empty()) {
       A2_LOG_NOTICE(fmt(MSG_SHARE_RATIO_REPORT,
                         shareRatio,
diff --git a/src/RpcMethodImpl.cc b/src/RpcMethodImpl.cc
index 4118104e..ddbb8435 100644
--- a/src/RpcMethodImpl.cc
+++ b/src/RpcMethodImpl.cc
@@ -697,8 +697,7 @@ void gatherProgressCommon
 
 #ifdef ENABLE_BITTORRENT
 void gatherBitTorrentMetadata
-(const std::shared_ptr<Dict>& btDict,
- const std::shared_ptr<TorrentAttribute>& torrentAttrs)
+(const std::shared_ptr<Dict>& btDict, TorrentAttribute* torrentAttrs)
 {
   if(!torrentAttrs->comment.empty()) {
     btDict->put(KEY_COMMENT, torrentAttrs->comment);
@@ -731,7 +730,7 @@ void gatherBitTorrentMetadata
 namespace {
 void gatherProgressBitTorrent
 (const std::shared_ptr<Dict>& entryDict,
- const std::shared_ptr<TorrentAttribute>& torrentAttrs,
+ TorrentAttribute* torrentAttrs,
  const std::shared_ptr<BtObject>& btObject,
  const std::vector<std::string>& keys)
 {
@@ -801,7 +800,7 @@ void gatherProgress
   gatherProgressCommon(entryDict, group, keys);
 #ifdef ENABLE_BITTORRENT
   if(group->getDownloadContext()->hasAttribute(CTX_ATTR_BT)) {
-    std::shared_ptr<TorrentAttribute> torrentAttrs =
+    auto torrentAttrs =
       bittorrent::getTorrentAttrs(group->getDownloadContext());
     const std::shared_ptr<BtObject>& btObject =
       e->getBtRegistry()->get(group->getGID());
diff --git a/src/RpcMethodImpl.h b/src/RpcMethodImpl.h
index 04265229..0a5a9b4a 100644
--- a/src/RpcMethodImpl.h
+++ b/src/RpcMethodImpl.h
@@ -599,8 +599,7 @@ void gatherProgressCommon
 #ifdef ENABLE_BITTORRENT
 // Helper function to store BitTorrent metadata from torrentAttrs.
 void gatherBitTorrentMetadata
-(const std::shared_ptr<Dict>& btDict,
- const std::shared_ptr<TorrentAttribute>& torrentAttrs);
+(const std::shared_ptr<Dict>& btDict, TorrentAttribute* torrentAttrs);
 #endif // ENABLE_BITTORRENT
 
 } // namespace rpc
diff --git a/src/TrackerWatcherCommand.cc b/src/TrackerWatcherCommand.cc
index 4c95236e..5b1d63da 100644
--- a/src/TrackerWatcherCommand.cc
+++ b/src/TrackerWatcherCommand.cc
@@ -328,8 +328,7 @@ namespace {
 bool backupTrackerIsAvailable
 (const std::shared_ptr<DownloadContext>& context)
 {
-  std::shared_ptr<TorrentAttribute> torrentAttrs =
-    bittorrent::getTorrentAttrs(context);
+  auto torrentAttrs = bittorrent::getTorrentAttrs(context);
   if(torrentAttrs->announceList.size() >= 2) {
     return true;
   }
diff --git a/src/UTMetadataPostDownloadHandler.cc b/src/UTMetadataPostDownloadHandler.cc
index da9f1a4a..82084243 100644
--- a/src/UTMetadataPostDownloadHandler.cc
+++ b/src/UTMetadataPostDownloadHandler.cc
@@ -59,7 +59,7 @@ bool UTMetadataPostDownloadHandler::Criteria::match
   const std::shared_ptr<DownloadContext>& dctx =
     requestGroup->getDownloadContext();
   if(dctx->hasAttribute(CTX_ATTR_BT)) {
-    std::shared_ptr<TorrentAttribute> attrs = bittorrent::getTorrentAttrs(dctx);
+    auto attrs = bittorrent::getTorrentAttrs(dctx);
     if(attrs->metadata.empty()) {
       return true;
     }
@@ -77,7 +77,7 @@ void UTMetadataPostDownloadHandler::getNextRequestGroups
 (std::vector<std::shared_ptr<RequestGroup> >& groups, RequestGroup* requestGroup)
 {
   const std::shared_ptr<DownloadContext>& dctx =requestGroup->getDownloadContext();
-  std::shared_ptr<TorrentAttribute> attrs = bittorrent::getTorrentAttrs(dctx);
+  auto attrs = bittorrent::getTorrentAttrs(dctx);
   std::string metadata =
     util::toString(requestGroup->getPieceStorage()->getDiskAdaptor());
   std::string torrent = bittorrent::metadata2Torrent(metadata, attrs);
diff --git a/src/UTMetadataRequestExtensionMessage.cc b/src/UTMetadataRequestExtensionMessage.cc
index f4444123..695be23e 100644
--- a/src/UTMetadataRequestExtensionMessage.cc
+++ b/src/UTMetadataRequestExtensionMessage.cc
@@ -76,7 +76,7 @@ std::string UTMetadataRequestExtensionMessage::toString() const
 
 void UTMetadataRequestExtensionMessage::doReceivedAction()
 {
-  std::shared_ptr<TorrentAttribute> attrs = bittorrent::getTorrentAttrs(dctx_);
+  auto attrs = bittorrent::getTorrentAttrs(dctx_);
   uint8_t id = peer_->getExtensionMessageID
     (ExtensionMessageRegistry::UT_METADATA);
   if(attrs->metadata.empty()) {
diff --git a/src/bittorrent_helper.cc b/src/bittorrent_helper.cc
index 07e9259f..e907ab0f 100644
--- a/src/bittorrent_helper.cc
+++ b/src/bittorrent_helper.cc
@@ -129,17 +129,16 @@ void extractPieceHash(const std::shared_ptr<DownloadContext>& ctx,
 
 namespace {
 void extractUrlList
-(const std::shared_ptr<TorrentAttribute>& torrent, std::vector<std::string>& uris,
+(TorrentAttribute* torrent, std::vector<std::string>& uris,
  const ValueBase* v)
 {
   class UrlListVisitor:public ValueBaseVisitor {
   private:
     std::vector<std::string>& uris_;
-    const std::shared_ptr<TorrentAttribute>& torrent_;
+    TorrentAttribute* torrent_;
   public:
     UrlListVisitor
-    (std::vector<std::string>& uris,
-     const std::shared_ptr<TorrentAttribute>& torrent):
+    (std::vector<std::string>& uris, TorrentAttribute* torrent):
       uris_(uris), torrent_(torrent) {}
 
     virtual void visit(const String& v)
@@ -195,7 +194,7 @@ OutputIterator createUri
 namespace {
 void extractFileEntries
 (const std::shared_ptr<DownloadContext>& ctx,
- const std::shared_ptr<TorrentAttribute>& torrent,
+ TorrentAttribute* torrent,
  const Dict* infoDict,
  const std::shared_ptr<Option>& option,
  const std::string& defaultName,
@@ -341,8 +340,7 @@ void extractFileEntries
 } // namespace
 
 namespace {
-void extractAnnounce
-(const std::shared_ptr<TorrentAttribute>& torrent, const Dict* rootDict)
+void extractAnnounce(TorrentAttribute* torrent, const Dict* rootDict)
 {
   const List* announceList = downcast<List>(rootDict->get(C_ANNOUNCE_LIST));
   if(announceList) {
@@ -376,8 +374,7 @@ void extractAnnounce
 } // namespace
 
 namespace {
-void extractNodes
-(const std::shared_ptr<TorrentAttribute>& torrent, const ValueBase* nodesListSrc)
+void extractNodes(TorrentAttribute* torrent, const ValueBase* nodesListSrc)
 {
   const List* nodesList = downcast<List>(nodesListSrc);
   if(nodesList) {
@@ -425,7 +422,7 @@ void processRootDictionary
     throw DL_ABORT_EX2(fmt(MSG_MISSING_BT_INFO, C_INFO.c_str()),
                        error_code::BITTORRENT_PARSE_ERROR);
   }
-  std::shared_ptr<TorrentAttribute> torrent(new TorrentAttribute());
+  std::unique_ptr<TorrentAttribute> torrent(new TorrentAttribute());
 
   // retrieve infoHash
   std::string encodedInfoDict = bencode2::encode(infoDict);
@@ -478,22 +475,22 @@ void processRootDictionary
   // This implemantation obeys HTTP-Seeding specification:
   // see http://www.getright.com/seedtorrent.html
   std::vector<std::string> urlList;
-  extractUrlList(torrent, urlList, rootDict->get(C_URL_LIST).get());
+  extractUrlList(torrent.get(), urlList, rootDict->get(C_URL_LIST).get());
   urlList.insert(urlList.end(), uris.begin(), uris.end());
   std::sort(urlList.begin(), urlList.end());
   urlList.erase(std::unique(urlList.begin(), urlList.end()), urlList.end());
 
   // retrieve file entries
   extractFileEntries
-    (ctx, torrent, infoDict, option, defaultName, overrideName, urlList);
+    (ctx, torrent.get(), infoDict, option, defaultName, overrideName, urlList);
   if((ctx->getTotalLength()+pieceLength-1)/pieceLength != numPieces) {
     throw DL_ABORT_EX2("Too few/many piece hash.",
                        error_code::BITTORRENT_PARSE_ERROR);
   }
   // retrieve announce
-  extractAnnounce(torrent, rootDict);
+  extractAnnounce(torrent.get(), rootDict);
   // retrieve nodes
-  extractNodes(torrent, rootDict->get(C_NODES).get());
+  extractNodes(torrent.get(), rootDict->get(C_NODES).get());
 
   const Integer* creationDate = downcast<Integer>(rootDict->get(C_CREATION_DATE));
   if(creationDate) {
@@ -513,7 +510,7 @@ void processRootDictionary
     torrent->createdBy = util::encodeNonUtf8(createdBy->s());
   }
 
-  ctx->setAttribute(CTX_ATTR_BT, torrent);
+  ctx->setAttribute(CTX_ATTR_BT, std::move(torrent));
 }
 } // namespace
 
@@ -621,16 +618,15 @@ void loadFromMemory(const std::shared_ptr<ValueBase>& torrent,
      uris);
 }
 
-std::shared_ptr<TorrentAttribute> getTorrentAttrs
+TorrentAttribute* getTorrentAttrs
 (const std::shared_ptr<DownloadContext>& dctx)
 {
   return getTorrentAttrs(dctx.get());
 }
 
-std::shared_ptr<TorrentAttribute> getTorrentAttrs(DownloadContext* dctx)
+TorrentAttribute* getTorrentAttrs(DownloadContext* dctx)
 {
-  return std::static_pointer_cast<TorrentAttribute>
-    (dctx->getAttribute(CTX_ATTR_BT));
+  return static_cast<TorrentAttribute*>(dctx->getAttribute(CTX_ATTR_BT));
 }
 
 const unsigned char* getInfoHash
@@ -907,7 +903,7 @@ void assertID
   }
 }
 
-std::shared_ptr<TorrentAttribute> parseMagnet(const std::string& magnet)
+std::unique_ptr<TorrentAttribute> parseMagnet(const std::string& magnet)
 {
   std::shared_ptr<Dict> r = magnet::parse(magnet);
   if(!r) {
@@ -919,7 +915,7 @@ std::shared_ptr<TorrentAttribute> parseMagnet(const std::string& magnet)
     throw DL_ABORT_EX2("Missing xt parameter in Magnet URI.",
                        error_code::MAGNET_PARSE_ERROR);
   }
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
+  auto attrs = make_unique<TorrentAttribute>();
   std::string infoHash;
   for(List::ValueType::const_iterator xtiter = xts->begin(),
         eoi = xts->end(); xtiter != eoi && infoHash.empty(); ++xtiter) {
@@ -969,12 +965,11 @@ std::shared_ptr<TorrentAttribute> parseMagnet(const std::string& magnet)
 void loadMagnet
 (const std::string& magnet, const std::shared_ptr<DownloadContext>& dctx)
 {
-  std::shared_ptr<TorrentAttribute> attrs = parseMagnet(magnet);
-  dctx->setAttribute(CTX_ATTR_BT, attrs);
+  dctx->setAttribute(CTX_ATTR_BT, parseMagnet(magnet));
 }
 
 std::string metadata2Torrent
-(const std::string& metadata, const std::shared_ptr<TorrentAttribute>& attrs)
+(const std::string& metadata, const TorrentAttribute* attrs)
 {
   std::string torrent = "d";
 
@@ -1001,7 +996,7 @@ std::string metadata2Torrent
   return torrent;
 }
 
-std::string torrent2Magnet(const std::shared_ptr<TorrentAttribute>& attrs)
+std::string torrent2Magnet(const TorrentAttribute* attrs)
 {
   std::string uri = "magnet:?";
   if(!attrs->infoHash.empty()) {
@@ -1038,8 +1033,7 @@ int getCompactLength(int family)
 }
 
 void removeAnnounceUri
-(const std::shared_ptr<TorrentAttribute>& attrs,
- const std::vector<std::string>& uris)
+(TorrentAttribute* attrs, const std::vector<std::string>& uris)
 {
   if(uris.empty()) {
     return;
@@ -1066,8 +1060,7 @@ void removeAnnounceUri
 }
 
 void addAnnounceUri
-(const std::shared_ptr<TorrentAttribute>& attrs,
- const std::vector<std::string>& uris)
+(TorrentAttribute* attrs, const std::vector<std::string>& uris)
 {
   for(std::vector<std::string>::const_iterator i = uris.begin(),
         eoi = uris.end(); i != eoi; ++i) {
@@ -1078,8 +1071,7 @@ void addAnnounceUri
 }
 
 void adjustAnnounceUri
-(const std::shared_ptr<TorrentAttribute>& attrs,
- const std::shared_ptr<Option>& option)
+(TorrentAttribute* attrs, const std::shared_ptr<Option>& option)
 {
   std::vector<std::string> excludeUris;
   std::vector<std::string> addUris;
diff --git a/src/bittorrent_helper.h b/src/bittorrent_helper.h
index 74d983f7..40c07e3d 100644
--- a/src/bittorrent_helper.h
+++ b/src/bittorrent_helper.h
@@ -117,7 +117,7 @@ void loadFromMemory(const std::shared_ptr<ValueBase>& torrent,
 // magnet:?xt=urn:btih:<info-hash>&dn=<name>&tr=<tracker-url>
 // <info-hash> comes in 2 flavors: 40bytes hexadecimal ascii string,
 // or 32bytes Base32 encoded string.
-std::shared_ptr<TorrentAttribute> parseMagnet(const std::string& magnet);
+std::unique_ptr<TorrentAttribute> parseMagnet(const std::string& magnet);
 
 // Parses BitTorrent Magnet URI and set them in ctx as a
 // bittorrent::BITTORRENT attibute. If parsing operation failed, an
@@ -149,8 +149,8 @@ void computeFastSet
 (std::vector<size_t>& fastSet, const std::string& ipaddr,
  size_t numPieces, const unsigned char* infoHash, size_t fastSetSize);
 
-std::shared_ptr<TorrentAttribute> getTorrentAttrs(DownloadContext* dctx);
-std::shared_ptr<TorrentAttribute> getTorrentAttrs
+TorrentAttribute* getTorrentAttrs(DownloadContext* dctx);
+TorrentAttribute* getTorrentAttrs
 (const std::shared_ptr<DownloadContext>& dctx);
 
 // Returns the value associated with INFO_HASH key in BITTORRENT
@@ -240,22 +240,20 @@ void assertID
 // Converts attrs into torrent data. This function does not guarantee
 // the returned string is valid torrent data.
 std::string metadata2Torrent
-(const std::string& metadata, const std::shared_ptr<TorrentAttribute>& attrs);
+(const std::string& metadata, const TorrentAttribute* attrs);
 
 // Constructs BitTorrent Magnet URI using attrs.
-std::string torrent2Magnet(const std::shared_ptr<TorrentAttribute>& attrs);
+std::string torrent2Magnet(const TorrentAttribute* attrs);
 
 // Removes announce URI in uris from attrs.  If uris contains '*', all
 // announce URIs are removed.
 void removeAnnounceUri
-(const std::shared_ptr<TorrentAttribute>& attrs,
- const std::vector<std::string>& uris);
+(TorrentAttribute* attrs, const std::vector<std::string>& uris);
 
 // Adds announce URI in uris to attrs. Each URI in uris creates its
 // own tier.
 void addAnnounceUri
-(const std::shared_ptr<TorrentAttribute>& attrs,
- const std::vector<std::string>& uris);
+(TorrentAttribute* attrs, const std::vector<std::string>& uris);
 
 // This helper function uses 2 option values: PREF_BT_TRACKER and
 // PREF_BT_EXCLUDE_TRACKER. First, the value of
@@ -263,8 +261,7 @@ void addAnnounceUri
 // and call removeAnnounceUri(). Then the value of PREF_BT_TRACKER is
 // converted to std::vector<std::string> and call addAnnounceUri().
 void adjustAnnounceUri
-(const std::shared_ptr<TorrentAttribute>& attrs,
- const std::shared_ptr<Option>& option);
+(TorrentAttribute* attrs, const std::shared_ptr<Option>& option);
 
 template<typename OutputIterator>
 void extractPeer(const ValueBase* peerData, int family, OutputIterator dest)
@@ -346,7 +343,7 @@ const char* getModeString(BtFileMode mode);
 template<typename Output>
 void print(Output& o, const std::shared_ptr<DownloadContext>& dctx)
 {
-  std::shared_ptr<TorrentAttribute> torrentAttrs = getTorrentAttrs(dctx);
+  TorrentAttribute* torrentAttrs = getTorrentAttrs(dctx);
   o.write("*** BitTorrent File Information ***\n");
   if(!torrentAttrs->comment.empty()) {
     o.printf("Comment: %s\n", torrentAttrs->comment.c_str());
diff --git a/src/download_helper.cc b/src/download_helper.cc
index cfed2c8a..58c22d1c 100644
--- a/src/download_helper.cc
+++ b/src/download_helper.cc
@@ -244,8 +244,7 @@ createBtMagnetRequestGroup
   rg->setFileAllocationEnabled(false);
   rg->setPreLocalFileCheckEnabled(false);
   bittorrent::loadMagnet(magnetLink, dctx);
-  std::shared_ptr<TorrentAttribute> torrentAttrs =
-    bittorrent::getTorrentAttrs(dctx);
+  auto torrentAttrs = bittorrent::getTorrentAttrs(dctx);
   bittorrent::adjustAnnounceUri(torrentAttrs, option);
   dctx->getFirstFileEntry()->setPath(torrentAttrs->name);
   rg->setDownloadContext(dctx);
diff --git a/test/BittorrentHelperTest.cc b/test/BittorrentHelperTest.cc
index 23c6b5b9..1fa7717d 100644
--- a/test/BittorrentHelperTest.cc
+++ b/test/BittorrentHelperTest.cc
@@ -260,7 +260,7 @@ void BittorrentHelperTest::testOverrideName()
 void BittorrentHelperTest::testGetAnnounceTier() {
   std::shared_ptr<DownloadContext> dctx(new DownloadContext());
   load(A2_TEST_DIR"/single.torrent", dctx, option_);
-  std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+  auto attrs = getTorrentAttrs(dctx);
   // There is 1 tier.
   CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList.size());
 
@@ -272,7 +272,7 @@ void BittorrentHelperTest::testGetAnnounceTier() {
 void BittorrentHelperTest::testGetAnnounceTierAnnounceList() {
   std::shared_ptr<DownloadContext> dctx(new DownloadContext());
   load(A2_TEST_DIR"/test.torrent", dctx, option_);
-  std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+  auto attrs = getTorrentAttrs(dctx);
   // There are 3 tiers.
   CPPUNIT_ASSERT_EQUAL((size_t)3, attrs->announceList.size());
 
@@ -534,7 +534,7 @@ void BittorrentHelperTest::testGetNodes()
     std::shared_ptr<DownloadContext> dctx(new DownloadContext());
     loadFromMemory(memory, dctx, option_, "default");
 
-    std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+    auto attrs = getTorrentAttrs(dctx);
     CPPUNIT_ASSERT_EQUAL((size_t)2, attrs->nodes.size());
     CPPUNIT_ASSERT_EQUAL(std::string("192.168.0.1"), attrs->nodes[0].first);
     CPPUNIT_ASSERT_EQUAL((uint16_t)6881, attrs->nodes[0].second);
@@ -554,7 +554,7 @@ void BittorrentHelperTest::testGetNodes()
     std::shared_ptr<DownloadContext> dctx(new DownloadContext());
     loadFromMemory(memory, dctx, option_, "default");
 
-    std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+    auto attrs = getTorrentAttrs(dctx);
     CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->nodes.size());
     CPPUNIT_ASSERT_EQUAL(std::string("192.168.0.2"), attrs->nodes[0].first);
     CPPUNIT_ASSERT_EQUAL((uint16_t)6882, attrs->nodes[0].second);
@@ -572,7 +572,7 @@ void BittorrentHelperTest::testGetNodes()
     std::shared_ptr<DownloadContext> dctx(new DownloadContext());
     loadFromMemory(memory, dctx, option_, "default");
 
-    std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+    auto attrs = getTorrentAttrs(dctx);
     CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->nodes.size());
     CPPUNIT_ASSERT_EQUAL(std::string("192.168.0.2"), attrs->nodes[0].first);
     CPPUNIT_ASSERT_EQUAL((uint16_t)6882, attrs->nodes[0].second);
@@ -590,7 +590,7 @@ void BittorrentHelperTest::testGetNodes()
     std::shared_ptr<DownloadContext> dctx(new DownloadContext());
     loadFromMemory(memory, dctx, option_, "default");
 
-    std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+    auto attrs = getTorrentAttrs(dctx);
     CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->nodes.size());
     CPPUNIT_ASSERT_EQUAL(std::string("192.168.0.2"), attrs->nodes[0].first);
     CPPUNIT_ASSERT_EQUAL((uint16_t)6882, attrs->nodes[0].second);
@@ -607,7 +607,7 @@ void BittorrentHelperTest::testGetNodes()
     std::shared_ptr<DownloadContext> dctx(new DownloadContext());
     loadFromMemory(memory, dctx, option_, "default");
 
-    std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+    auto attrs = getTorrentAttrs(dctx);
     CPPUNIT_ASSERT_EQUAL((size_t)0, attrs->nodes.size());
   }
   {
@@ -623,7 +623,7 @@ void BittorrentHelperTest::testGetNodes()
     std::shared_ptr<DownloadContext> dctx(new DownloadContext());
     loadFromMemory(memory, dctx, option_, "default");
 
-    std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+    auto attrs = getTorrentAttrs(dctx);
     CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->nodes.size());
     CPPUNIT_ASSERT_EQUAL(std::string("192.168.0.2"), attrs->nodes[0].first);
     CPPUNIT_ASSERT_EQUAL((uint16_t)6882, attrs->nodes[0].second);
@@ -749,7 +749,7 @@ void BittorrentHelperTest::testMetadata() {
   std::shared_ptr<ValueBase> tr = bencode2::decode(torrentData);
   std::shared_ptr<ValueBase> infoDic = downcast<Dict>(tr)->get("info");
   std::string metadata = bencode2::encode(infoDic);
-  std::shared_ptr<TorrentAttribute> attrs = getTorrentAttrs(dctx);
+  auto attrs = getTorrentAttrs(dctx);
   CPPUNIT_ASSERT(metadata == attrs->metadata);
   CPPUNIT_ASSERT_EQUAL(metadata.size(), attrs->metadataSize);
 }
@@ -759,7 +759,7 @@ void BittorrentHelperTest::testParseMagnet()
   std::string magnet =
     "magnet:?xt=urn:btih:248d0a1cd08284299de78d5c1ed359bb46717d8c&dn=aria2"
     "&tr=http://tracker1&tr=http://tracker2";
-  std::shared_ptr<TorrentAttribute> attrs = bittorrent::parseMagnet(magnet);
+  auto attrs = bittorrent::parseMagnet(magnet);
   CPPUNIT_ASSERT_EQUAL(std::string("248d0a1cd08284299de78d5c1ed359bb46717d8c"),
                        util::toHex(attrs->infoHash));
   CPPUNIT_ASSERT_EQUAL(std::string("[METADATA]aria2"), attrs->name);
@@ -788,7 +788,7 @@ void BittorrentHelperTest::testParseMagnet_base32()
   std::string infoHash = "248d0a1cd08284299de78d5c1ed359bb46717d8c";
   std::string base32InfoHash = base32::encode(fromHex(infoHash));
   std::string magnet = "magnet:?xt=urn:btih:"+base32InfoHash+"&dn=aria2";
-  std::shared_ptr<TorrentAttribute> attrs = bittorrent::parseMagnet(magnet);
+  auto attrs = bittorrent::parseMagnet(magnet);
   CPPUNIT_ASSERT_EQUAL
     (std::string("248d0a1cd08284299de78d5c1ed359bb46717d8c"),
      util::toHex(attrs->infoHash));
@@ -796,19 +796,19 @@ void BittorrentHelperTest::testParseMagnet_base32()
 
 void BittorrentHelperTest::testMetadata2Torrent()
 {
+  TorrentAttribute attrs;
   std::string metadata = "METADATA";
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
   CPPUNIT_ASSERT_EQUAL
-    (std::string("d4:infoMETADATAe"), metadata2Torrent(metadata, attrs));
-  attrs->announceList.push_back(std::vector<std::string>());
-  attrs->announceList[0].push_back("http://localhost/announce");
+    (std::string("d4:infoMETADATAe"), metadata2Torrent(metadata, &attrs));
+  attrs.announceList.push_back(std::vector<std::string>());
+  attrs.announceList[0].push_back("http://localhost/announce");
   CPPUNIT_ASSERT_EQUAL
     (std::string("d"
                  "13:announce-list"
                  "ll25:http://localhost/announceee"
                  "4:infoMETADATA"
                  "e"),
-     metadata2Torrent(metadata, attrs));
+     metadata2Torrent(metadata, &attrs));
 }
 
 void BittorrentHelperTest::testTorrent2Magnet()
@@ -927,78 +927,78 @@ void BittorrentHelperTest::testUnpackcompact()
 
 void BittorrentHelperTest::testRemoveAnnounceUri()
 {
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
+  TorrentAttribute attrs;
   std::vector<std::string> tier1;
   tier1.push_back("http://host1/announce");
   std::vector<std::string> tier2;
   tier2.push_back("http://host2/announce");
   tier2.push_back("http://host3/announce");
-  attrs->announceList.push_back(tier1);
-  attrs->announceList.push_back(tier2);
+  attrs.announceList.push_back(tier1);
+  attrs.announceList.push_back(tier2);
 
   std::vector<std::string> removeUris;
   removeUris.push_back(tier1[0]);
   removeUris.push_back(tier2[0]);
-  removeAnnounceUri(attrs, removeUris);
-  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList.size());
+  removeAnnounceUri(&attrs, removeUris);
+  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs.announceList.size());
   CPPUNIT_ASSERT_EQUAL(std::string("http://host3/announce"),
-                       attrs->announceList[0][0]);
+                       attrs.announceList[0][0]);
 
   removeUris.clear();
   removeUris.push_back("*");
 
-  removeAnnounceUri(attrs, removeUris);
-  CPPUNIT_ASSERT(attrs->announceList.empty());
+  removeAnnounceUri(&attrs, removeUris);
+  CPPUNIT_ASSERT(attrs.announceList.empty());
 }
 
 void BittorrentHelperTest::testAddAnnounceUri()
 {
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
+  TorrentAttribute attrs;
   std::vector<std::string> addUris;
   addUris.push_back("http://host1/announce");
   addUris.push_back("http://host2/announce");
-  addAnnounceUri(attrs, addUris);
-  CPPUNIT_ASSERT_EQUAL((size_t)2, attrs->announceList.size());
+  addAnnounceUri(&attrs, addUris);
+  CPPUNIT_ASSERT_EQUAL((size_t)2, attrs.announceList.size());
 
-  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList[0].size());
+  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs.announceList[0].size());
   CPPUNIT_ASSERT_EQUAL(std::string("http://host1/announce"),
-                       attrs->announceList[0][0]);
+                       attrs.announceList[0][0]);
 
-  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList[1].size());
+  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs.announceList[1].size());
   CPPUNIT_ASSERT_EQUAL(std::string("http://host2/announce"),
-                       attrs->announceList[1][0]);
+                       attrs.announceList[1][0]);
 }
 
 void BittorrentHelperTest::testAdjustAnnounceUri()
 {
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
+  TorrentAttribute attrs;
   std::vector<std::string> tier1;
   tier1.push_back("http://host1/announce");
   std::vector<std::string> tier2;
   tier2.push_back("http://host2/announce");
   tier2.push_back("http://host3/announce");
-  attrs->announceList.push_back(tier1);
-  attrs->announceList.push_back(tier2);
+  attrs.announceList.push_back(tier1);
+  attrs.announceList.push_back(tier2);
 
   std::shared_ptr<Option> option(new Option());
   option->put(PREF_BT_TRACKER, "http://host1/announce,http://host4/announce");
   option->put(PREF_BT_EXCLUDE_TRACKER,
               "http://host1/announce,http://host2/announce");
-  adjustAnnounceUri(attrs, option);
+  adjustAnnounceUri(&attrs, option);
 
-  CPPUNIT_ASSERT_EQUAL((size_t)3, attrs->announceList.size());
+  CPPUNIT_ASSERT_EQUAL((size_t)3, attrs.announceList.size());
 
-  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList[0].size());
+  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs.announceList[0].size());
   CPPUNIT_ASSERT_EQUAL(std::string("http://host3/announce"),
-                       attrs->announceList[0][0]);
+                       attrs.announceList[0][0]);
 
-  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList[1].size());
+  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs.announceList[1].size());
   CPPUNIT_ASSERT_EQUAL(std::string("http://host1/announce"),
-                       attrs->announceList[1][0]);
+                       attrs.announceList[1][0]);
 
-  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs->announceList[2].size());
+  CPPUNIT_ASSERT_EQUAL((size_t)1, attrs.announceList[2].size());
   CPPUNIT_ASSERT_EQUAL(std::string("http://host4/announce"),
-                       attrs->announceList[2][0]);
+                       attrs.announceList[2][0]);
 }
 
 } // namespace bittorrent
diff --git a/test/BtDependencyTest.cc b/test/BtDependencyTest.cc
index 6fc9c9e8..9a3c1e72 100644
--- a/test/BtDependencyTest.cc
+++ b/test/BtDependencyTest.cc
@@ -192,9 +192,8 @@ void BtDependencyTest::testResolve_metadata()
   pieceStorage->setDiskAdaptor(diskAdaptor);
   pieceStorage->setDownloadFinished(true);
   dependee->setPieceStorage(pieceStorage);
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
-  dependee->getDownloadContext()->setAttribute(CTX_ATTR_BT, attrs);
-
+  dependee->getDownloadContext()->setAttribute(CTX_ATTR_BT,
+                                               make_unique<TorrentAttribute>());
   BtDependency dep(dependant.get(), dependee);
   CPPUNIT_ASSERT(dep.resolve());
 
diff --git a/test/BtRegistryTest.cc b/test/BtRegistryTest.cc
index 7bbd40e3..66db5be6 100644
--- a/test/BtRegistryTest.cc
+++ b/test/BtRegistryTest.cc
@@ -66,13 +66,16 @@ void BtRegistryTest::testGetDownloadContext_infoHash()
 {
   BtRegistry btRegistry;
   addTwoDownloadContext(btRegistry);
-  std::shared_ptr<TorrentAttribute> attrs1(new TorrentAttribute());
-  attrs1->infoHash = "hash1";
-  std::shared_ptr<TorrentAttribute> attrs2(new TorrentAttribute());
-  attrs2->infoHash = "hash2";
-  btRegistry.getDownloadContext(1)->setAttribute(CTX_ATTR_BT, attrs1);
-  btRegistry.getDownloadContext(2)->setAttribute(CTX_ATTR_BT, attrs2);
-
+  {
+    auto attrs1 = make_unique<TorrentAttribute>();
+    attrs1->infoHash = "hash1";
+    auto attrs2 = make_unique<TorrentAttribute>();
+    attrs2->infoHash = "hash2";
+    btRegistry.getDownloadContext(1)->setAttribute(CTX_ATTR_BT,
+                                                   std::move(attrs1));
+    btRegistry.getDownloadContext(2)->setAttribute(CTX_ATTR_BT,
+                                                   std::move(attrs2));
+  }
   CPPUNIT_ASSERT(btRegistry.getDownloadContext("hash1"));
   CPPUNIT_ASSERT(btRegistry.getDownloadContext("hash1").get() ==
                  btRegistry.getDownloadContext(1).get());
diff --git a/test/DefaultBtAnnounceTest.cc b/test/DefaultBtAnnounceTest.cc
index 2d9c3c09..1fc4c32e 100644
--- a/test/DefaultBtAnnounceTest.cc
+++ b/test/DefaultBtAnnounceTest.cc
@@ -61,9 +61,11 @@ public:
     std::string peerId = "-aria2-ultrafastdltl";
 
     dctx_.reset(new DownloadContext(pieceLength, totalLength));
-    std::shared_ptr<TorrentAttribute> torrentAttrs(new TorrentAttribute());
-    torrentAttrs->infoHash = std::string(vbegin(infoHash), vend(infoHash));
-    dctx_->setAttribute(CTX_ATTR_BT, torrentAttrs);
+    {
+      auto torrentAttrs = make_unique<TorrentAttribute>();
+      torrentAttrs->infoHash = std::string(vbegin(infoHash), vend(infoHash));
+      dctx_->setAttribute(CTX_ATTR_BT, std::move(torrentAttrs));
+    }
     dctx_->getNetStat().updateDownloadLength(pieceLength*5);
     dctx_->getNetStat().updateUploadLength(pieceLength*6);
     bittorrent::setStaticPeerId(peerId);
diff --git a/test/DefaultBtProgressInfoFileTest.cc b/test/DefaultBtProgressInfoFileTest.cc
index 8e0dad88..fdbf0e88 100644
--- a/test/DefaultBtProgressInfoFileTest.cc
+++ b/test/DefaultBtProgressInfoFileTest.cc
@@ -70,9 +70,11 @@ public:
     };
 
     dctx_.reset(new DownloadContext());
-    std::shared_ptr<TorrentAttribute> torrentAttrs(new TorrentAttribute());
-    torrentAttrs->infoHash = std::string(vbegin(infoHash), vend(infoHash));
-    dctx_->setAttribute(CTX_ATTR_BT, torrentAttrs);
+    {
+      auto torrentAttrs = make_unique<TorrentAttribute>();
+      torrentAttrs->infoHash = std::string(vbegin(infoHash), vend(infoHash));
+      dctx_->setAttribute(CTX_ATTR_BT, std::move(torrentAttrs));
+    }
     const std::shared_ptr<FileEntry> fileEntries[] = {
       std::shared_ptr<FileEntry>(new FileEntry("/path/to/file",totalLength,0))
     };
diff --git a/test/DownloadHelperTest.cc b/test/DownloadHelperTest.cc
index 8503d330..293491ab 100644
--- a/test/DownloadHelperTest.cc
+++ b/test/DownloadHelperTest.cc
@@ -336,8 +336,7 @@ void DownloadHelperTest::testCreateRequestGroupForBitTorrent()
       CPPUNIT_ASSERT_EQUAL(array[i]+"/aria2-test/aria2/src/aria2c", uris[i]);
     }
     CPPUNIT_ASSERT_EQUAL(5, group->getNumConcurrentCommand());
-    std::shared_ptr<TorrentAttribute> attrs =
-      bittorrent::getTorrentAttrs(group->getDownloadContext());
+    auto attrs = bittorrent::getTorrentAttrs(group->getDownloadContext());
     // http://tracker1 was deleted.
     CPPUNIT_ASSERT_EQUAL((size_t)2, attrs->announceList.size());
   }
diff --git a/test/HandshakeExtensionMessageTest.cc b/test/HandshakeExtensionMessageTest.cc
index 218b3e27..bdd16cdf 100644
--- a/test/HandshakeExtensionMessageTest.cc
+++ b/test/HandshakeExtensionMessageTest.cc
@@ -97,8 +97,7 @@ void HandshakeExtensionMessageTest::testDoReceivedAction()
   RequestGroup rg(GroupId::create(), op);
   rg.setDownloadContext(dctx);
 
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
-  dctx->setAttribute(CTX_ATTR_BT, attrs);
+  dctx->setAttribute(CTX_ATTR_BT, make_unique<TorrentAttribute>());
   dctx->markTotalLengthIsUnknown();
 
   std::shared_ptr<Peer> peer(new Peer("192.168.0.1", 0));
@@ -122,6 +121,7 @@ void HandshakeExtensionMessageTest::testDoReceivedAction()
                        peer->getExtensionMessageID
                        (ExtensionMessageRegistry::UT_METADATA));
   CPPUNIT_ASSERT(peer->isSeeder());
+  auto attrs = bittorrent::getTorrentAttrs(dctx);
   CPPUNIT_ASSERT_EQUAL((size_t)1024, attrs->metadataSize);
   CPPUNIT_ASSERT_EQUAL((int64_t)1024, dctx->getTotalLength());
   CPPUNIT_ASSERT(dctx->knowsTotalLength());
diff --git a/test/MSEHandshakeTest.cc b/test/MSEHandshakeTest.cc
index 002a86e2..a6b02126 100644
--- a/test/MSEHandshakeTest.cc
+++ b/test/MSEHandshakeTest.cc
@@ -33,9 +33,11 @@ public:
     dctx_.reset(new DownloadContext());
     unsigned char infoHash[20];
     memset(infoHash, 0, sizeof(infoHash));
-    std::shared_ptr<TorrentAttribute> torrentAttrs(new TorrentAttribute());
-    torrentAttrs->infoHash = std::string(vbegin(infoHash), vend(infoHash));
-    dctx_->setAttribute(CTX_ATTR_BT, torrentAttrs);
+    {
+      auto torrentAttrs = make_unique<TorrentAttribute>();
+      torrentAttrs->infoHash = std::string(vbegin(infoHash), vend(infoHash));
+      dctx_->setAttribute(CTX_ATTR_BT, std::move(torrentAttrs));
+    }
   }
 
   void testHandshake();
diff --git a/test/RpcMethodTest.cc b/test/RpcMethodTest.cc
index 9331e664..570301a2 100644
--- a/test/RpcMethodTest.cc
+++ b/test/RpcMethodTest.cc
@@ -949,7 +949,7 @@ void RpcMethodTest::testGatherBitTorrentMetadata()
   CPPUNIT_ASSERT_EQUAL(std::string("http://tracker3"),
                        downcast<String>(downcast<List>(announceList->get(2))->get(0))->s());
   // Remove some keys
-  std::shared_ptr<TorrentAttribute> modBtAttrs = bittorrent::getTorrentAttrs(dctx);
+  auto modBtAttrs = bittorrent::getTorrentAttrs(dctx);
   modBtAttrs->comment.clear();
   modBtAttrs->creationDate = 0;
   modBtAttrs->mode = BT_FILE_MODE_NONE;
diff --git a/test/UTMetadataDataExtensionMessageTest.cc b/test/UTMetadataDataExtensionMessageTest.cc
index 58770cbf..be6c2529 100644
--- a/test/UTMetadataDataExtensionMessageTest.cc
+++ b/test/UTMetadataDataExtensionMessageTest.cc
@@ -73,7 +73,6 @@ void UTMetadataDataExtensionMessageTest::testDoReceivedAction()
   std::shared_ptr<UTMetadataRequestTracker> tracker
     (new UTMetadataRequestTracker());
   std::shared_ptr<DownloadContext> dctx(new DownloadContext());
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
 
   std::string piece0 = std::string(METADATA_PIECE_SIZE, '0');
   std::string piece1 = std::string(METADATA_PIECE_SIZE, '1');
@@ -83,9 +82,11 @@ void UTMetadataDataExtensionMessageTest::testDoReceivedAction()
   message_digest::digest(infoHash, INFO_HASH_LENGTH,
                          MessageDigest::sha1(),
                          metadata.data(), metadata.size());
-  attrs->infoHash = std::string(&infoHash[0], &infoHash[20]);
-  dctx->setAttribute(CTX_ATTR_BT, attrs);
-
+  {
+    auto attrs = make_unique<TorrentAttribute>();
+    attrs->infoHash = std::string(&infoHash[0], &infoHash[20]);
+    dctx->setAttribute(CTX_ATTR_BT, std::move(attrs));
+  }
   UTMetadataDataExtensionMessage m(1);
   m.setPieceStorage(pieceStorage);
   m.setUTMetadataRequestTracker(tracker.get());
diff --git a/test/UTMetadataPostDownloadHandlerTest.cc b/test/UTMetadataPostDownloadHandlerTest.cc
index e98ce000..81b99115 100644
--- a/test/UTMetadataPostDownloadHandlerTest.cc
+++ b/test/UTMetadataPostDownloadHandlerTest.cc
@@ -52,11 +52,11 @@ void UTMetadataPostDownloadHandlerTest::testCanHandle()
 
   CPPUNIT_ASSERT(!handler.canHandle(requestGroup_.get()));
 
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
-  dctx_->setAttribute(CTX_ATTR_BT, attrs);
+  dctx_->setAttribute(CTX_ATTR_BT, make_unique<TorrentAttribute>());
 
   CPPUNIT_ASSERT(handler.canHandle(requestGroup_.get()));
 
+  auto attrs = bittorrent::getTorrentAttrs(dctx_);
   // Only checks whether metadata is empty or not
   attrs->metadata = "metadata";
 
@@ -77,14 +77,16 @@ void UTMetadataPostDownloadHandlerTest::testGetNextRequestGroups()
     (infoHash, sizeof(infoHash), MessageDigest::sha1(),
      reinterpret_cast<const unsigned char*>(metadata.data()), metadata.size());
   dctx_->getFirstFileEntry()->setLength(metadata.size());
-  std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
-  attrs->infoHash = std::string(&infoHash[0], &infoHash[20]);
   std::vector<std::vector<std::string> > announceList;
   std::vector<std::string> announceTier;
   announceTier.push_back("http://tracker");
   announceList.push_back(announceTier);
-  attrs->announceList = announceList;
-  dctx_->setAttribute(CTX_ATTR_BT, attrs);
+  {
+    auto attrs = make_unique<TorrentAttribute>();
+    attrs->infoHash = std::string(&infoHash[0], &infoHash[20]);
+    attrs->announceList = announceList;
+    dctx_->setAttribute(CTX_ATTR_BT, std::move(attrs));
+  }
   requestGroup_->setDiskWriterFactory
     (std::shared_ptr<DiskWriterFactory>(new ByteArrayDiskWriterFactory()));
   requestGroup_->initPieceStorage();
@@ -99,8 +101,7 @@ void UTMetadataPostDownloadHandlerTest::testGetNextRequestGroups()
   CPPUNIT_ASSERT_EQUAL((size_t)1, results.size());
   std::shared_ptr<RequestGroup> newRg = results.front();
   std::shared_ptr<DownloadContext> newDctx = newRg->getDownloadContext();
-  std::shared_ptr<TorrentAttribute> newAttrs =
-    bittorrent::getTorrentAttrs(newDctx);
+  auto newAttrs = bittorrent::getTorrentAttrs(newDctx);
   CPPUNIT_ASSERT_EQUAL(bittorrent::getInfoHashString(dctx_),
                        bittorrent::getInfoHashString(newDctx));
   const std::vector<std::vector<std::string> >& newAnnounceList =
diff --git a/test/UTMetadataRequestExtensionMessageTest.cc b/test/UTMetadataRequestExtensionMessageTest.cc
index 97ba5a2f..f1b925cb 100644
--- a/test/UTMetadataRequestExtensionMessageTest.cc
+++ b/test/UTMetadataRequestExtensionMessageTest.cc
@@ -42,7 +42,7 @@ public:
     dispatcher_.reset(new MockBtMessageDispatcher());
     dctx_.reset(new DownloadContext());
     std::shared_ptr<TorrentAttribute> attrs(new TorrentAttribute());
-    dctx_->setAttribute(CTX_ATTR_BT, attrs);
+    dctx_->setAttribute(CTX_ATTR_BT, make_unique<TorrentAttribute>());
     peer_.reset(new Peer("host", 6880));
     peer_->allocateSessionResource(0, 0);
     peer_->setExtension(ExtensionMessageRegistry::UT_METADATA, 1);
@@ -125,7 +125,7 @@ void UTMetadataRequestExtensionMessageTest::testDoReceivedAction_data()
   msg.setBtMessageDispatcher(dispatcher_.get());
 
   size_t metadataSize = METADATA_PIECE_SIZE*2;
-  std::shared_ptr<TorrentAttribute> attrs = bittorrent::getTorrentAttrs(dctx_);
+  auto attrs = bittorrent::getTorrentAttrs(dctx_);
   std::string first(METADATA_PIECE_SIZE, '0');
   std::string second(METADATA_PIECE_SIZE, '1');
   attrs->metadata = first+second;