diff --git a/src/BtPieceMessage.cc b/src/BtPieceMessage.cc
index 5abc35dc..fb57a171 100644
--- a/src/BtPieceMessage.cc
+++ b/src/BtPieceMessage.cc
@@ -214,16 +214,13 @@ void BtPieceMessage::send()
 void BtPieceMessage::pushPieceData(int64_t offset, int32_t length) const
 {
   assert(length <= 16*1024);
-  array_ptr<unsigned char> buf
-    (new unsigned char[length+MESSAGE_HEADER_LENGTH]);
-  createMessageHeader(buf);
+  auto buf = make_unique<unsigned char[]>(length+MESSAGE_HEADER_LENGTH);
+  createMessageHeader(buf.get());
   ssize_t r;
-  r = getPieceStorage()->getDiskAdaptor()->readData(buf+MESSAGE_HEADER_LENGTH,
-                                                    length, offset);
+  r = getPieceStorage()->getDiskAdaptor()->readData
+    (buf.get()+MESSAGE_HEADER_LENGTH, length, offset);
   if(r == length) {
-    unsigned char* dbuf = buf;
-    buf.reset(0);
-    getPeerConnection()->pushBytes(dbuf, length+MESSAGE_HEADER_LENGTH,
+    getPeerConnection()->pushBytes(buf.release(), length+MESSAGE_HEADER_LENGTH,
                                    make_unique<PieceSendUpdate>
                                    (getPeer(), MESSAGE_HEADER_LENGTH));
     // To avoid upload rate overflow, we update the length here at
diff --git a/src/DefaultBtProgressInfoFile.cc b/src/DefaultBtProgressInfoFile.cc
index 5f5c2ca9..ed5fd8f8 100644
--- a/src/DefaultBtProgressInfoFile.cc
+++ b/src/DefaultBtProgressInfoFile.cc
@@ -242,18 +242,17 @@ void DefaultBtProgressInfoFile::load()
     throw DL_ABORT_EX(fmt("Invalid info hash length: %d", infoHashLength));
   }
   if(infoHashLength > 0) {
-    array_ptr<unsigned char> savedInfoHash(new unsigned char[infoHashLength]);
-    READ_CHECK(fp, static_cast<unsigned char*>(savedInfoHash),
-               infoHashLength);
+    auto savedInfoHash = make_unique<unsigned char[]>((size_t)infoHashLength);
+    READ_CHECK(fp, savedInfoHash.get(), infoHashLength);
 #ifdef ENABLE_BITTORRENT
     if(infoHashCheckEnabled) {
       const unsigned char* infoHash = bittorrent::getInfoHash(dctx_);
       if(infoHashLength != INFO_HASH_LENGTH ||
-         memcmp(savedInfoHash, infoHash, INFO_HASH_LENGTH) != 0) {
+         memcmp(savedInfoHash.get(), infoHash, INFO_HASH_LENGTH) != 0) {
         throw DL_ABORT_EX
           (fmt("info hash mismatch. expected: %s, actual: %s",
                util::toHex(infoHash, INFO_HASH_LENGTH).c_str(),
-               util::toHex(savedInfoHash, infoHashLength).c_str()
+               util::toHex(savedInfoHash.get(), infoHashLength).c_str()
                ));
       }
     }
@@ -302,11 +301,10 @@ void DefaultBtProgressInfoFile::load()
            bitfieldLength));
   }
 
-  array_ptr<unsigned char> savedBitfield(new unsigned char[bitfieldLength]);
-  READ_CHECK(fp, static_cast<unsigned char*>(savedBitfield),
-             bitfieldLength);
+  auto savedBitfield = make_unique<unsigned char[]>((size_t)bitfieldLength);
+  READ_CHECK(fp, savedBitfield.get(), bitfieldLength);
   if(pieceLength == static_cast<uint32_t>(dctx_->getPieceLength())) {
-    pieceStorage_->setBitfield(savedBitfield, bitfieldLength);
+    pieceStorage_->setBitfield(savedBitfield.get(), bitfieldLength);
 
     uint32_t numInFlightPiece;
     READ_CHECK(fp, &numInFlightPiece, sizeof(numInFlightPiece));
@@ -345,11 +343,10 @@ void DefaultBtProgressInfoFile::load()
                static_cast<unsigned long>(piece->getBitfieldLength()),
                bitfieldLength));
       }
-      array_ptr<unsigned char> pieceBitfield
-        (new unsigned char[bitfieldLength]);
-      READ_CHECK(fp, static_cast<unsigned char*>(pieceBitfield),
-                 bitfieldLength);
-      piece->setBitfield(pieceBitfield, bitfieldLength);
+      auto pieceBitfield = make_unique<unsigned char[]>
+        ((size_t)bitfieldLength);
+      READ_CHECK(fp, pieceBitfield.get(), bitfieldLength);
+      piece->setBitfield(pieceBitfield.get(), bitfieldLength);
 
 #ifdef ENABLE_MESSAGE_DIGEST
 
@@ -367,7 +364,7 @@ void DefaultBtProgressInfoFile::load()
       numInFlightPiece = ntohl(numInFlightPiece);
     }
     BitfieldMan src(pieceLength, totalLength);
-    src.setBitfield(savedBitfield, bitfieldLength);
+    src.setBitfield(savedBitfield.get(), bitfieldLength);
     if((src.getCompletedLength() || numInFlightPiece) &&
        !option_->getAsBool(PREF_ALLOW_PIECE_LENGTH_CHANGE)) {
       throw DOWNLOAD_FAILURE_EXCEPTION2
diff --git a/src/DefaultBtRequestFactory.cc b/src/DefaultBtRequestFactory.cc
index 277f28b7..a7cd4838 100644
--- a/src/DefaultBtRequestFactory.cc
+++ b/src/DefaultBtRequestFactory.cc
@@ -197,9 +197,9 @@ DefaultBtRequestFactory::createRequestMessagesOnEndGame(size_t max)
       itr != eoi && requests.size() < max; ++itr) {
     auto& piece = *itr;
     const size_t mislen = piece->getBitfieldLength();
-    array_ptr<unsigned char> misbitfield(new unsigned char[mislen]);
+    auto misbitfield = make_unique<unsigned char[]>(mislen);
 
-    piece->getAllMissingBlockIndexes(misbitfield, mislen);
+    piece->getAllMissingBlockIndexes(misbitfield.get(), mislen);
 
     auto missingBlockIndexes = std::vector<size_t>{};
     size_t blockIndex = 0;
diff --git a/src/DefaultPieceStorage.cc b/src/DefaultPieceStorage.cc
index cee96df9..9fc33367 100644
--- a/src/DefaultPieceStorage.cc
+++ b/src/DefaultPieceStorage.cc
@@ -185,12 +185,12 @@ void DefaultPieceStorage::getMissingPiece
  cuid_t cuid)
 {
   const size_t mislen = bitfieldMan_->getBitfieldLength();
-  array_ptr<unsigned char> misbitfield(new unsigned char[mislen]);
+  auto misbitfield = make_unique<unsigned char[]>(mislen);
   size_t blocks = bitfieldMan_->countBlock();
   size_t misBlock = 0;
   if(isEndGame()) {
     bool r = bitfieldMan_->getAllMissingIndexes
-      (misbitfield, mislen, bitfield, length);
+      (misbitfield.get(), mislen, bitfield, length);
     if(!r) {
       return;
     }
@@ -214,15 +214,15 @@ void DefaultPieceStorage::getMissingPiece
     }
   } else {
     bool r = bitfieldMan_->getAllMissingUnusedIndexes
-      (misbitfield, mislen, bitfield, length);
+      (misbitfield.get(), mislen, bitfield, length);
     if(!r) {
       return;
     }
     while(misBlock < minMissingBlocks) {
       size_t index;
-      if(pieceSelector_->select(index, misbitfield, blocks)) {
+      if(pieceSelector_->select(index, misbitfield.get(), blocks)) {
         pieces.push_back(checkOutPiece(index, cuid));
-        bitfield::flipBit(misbitfield, blocks, index);
+        bitfield::flipBit(misbitfield.get(), blocks, index);
         misBlock += pieces.back()->countMissingBlock();
       } else {
         break;
diff --git a/src/MSEHandshake.cc b/src/MSEHandshake.cc
index a6e43f21..332e8cfa 100644
--- a/src/MSEHandshake.cc
+++ b/src/MSEHandshake.cc
@@ -128,15 +128,13 @@ void MSEHandshake::sendPublicKey()
 {
   A2_LOG_DEBUG(fmt("CUID#%" PRId64 " - Sending public key.",
                    cuid_));
-  unsigned char* buf = new unsigned char[KEY_LENGTH+MAX_PAD_LENGTH];
-  array_ptr<unsigned char> bufp(buf);
-  dh_->getPublicKey(buf, KEY_LENGTH);
+  auto buf = make_unique<unsigned char[]>(KEY_LENGTH+MAX_PAD_LENGTH);
+  dh_->getPublicKey(buf.get(), KEY_LENGTH);
 
   size_t padLength =
     SimpleRandomizer::getInstance()->getRandomNumber(MAX_PAD_LENGTH+1);
-  dh_->generateNonce(buf+KEY_LENGTH, padLength);
-  socketBuffer_.pushBytes(buf, KEY_LENGTH+padLength);
-  bufp.reset(0);
+  dh_->generateNonce(buf.get()+KEY_LENGTH, padLength);
+  socketBuffer_.pushBytes(buf.release(), KEY_LENGTH+padLength);
 }
 
 void MSEHandshake::read()
@@ -271,23 +269,23 @@ void MSEHandshake::sendInitiatorStep2()
 {
   A2_LOG_DEBUG(fmt("CUID#%" PRId64 " - Sending negotiation step2.", cuid_));
   // Assuming no exception
-  unsigned char* md = new unsigned char[20];
-  createReq1Hash(md);
-  socketBuffer_.pushBytes(md, 20);
+  auto md = make_unique<unsigned char[]>((size_t)20);
+  createReq1Hash(md.get());
+  socketBuffer_.pushBytes(md.release(), 20);
   // Assuming no exception
-  md = new unsigned char[20];
-  createReq23Hash(md, infoHash_);
-  socketBuffer_.pushBytes(md, 20);
+  md = make_unique<unsigned char[]>((size_t)20);
+  createReq23Hash(md.get(), infoHash_);
+  socketBuffer_.pushBytes(md.release(), 20);
   // buffer is filled in this order:
   //   VC(VC_LENGTH bytes),
   //   crypto_provide(CRYPTO_BITFIELD_LENGTH bytes),
   //   len(padC)(2 bytes),
   //   padC(len(padC) bytes <= MAX_PAD_LENGTH),
   //   len(IA)(2 bytes)
-  unsigned char* buffer = new unsigned char
-    [40+VC_LENGTH+CRYPTO_BITFIELD_LENGTH+2+MAX_PAD_LENGTH+2];
-  array_ptr<unsigned char> bufp(buffer);
-  unsigned char* ptr = buffer;
+  auto buffer = make_unique<unsigned char[]>(40+VC_LENGTH+
+                                             CRYPTO_BITFIELD_LENGTH+2+
+                                             MAX_PAD_LENGTH+2);
+  unsigned char* ptr = buffer.get();
   // VC
   memcpy(ptr, VC, sizeof(VC));
   ptr += sizeof(VC);
@@ -317,8 +315,8 @@ void MSEHandshake::sendInitiatorStep2()
     memcpy(ptr, &iaLengthBE, sizeof(iaLengthBE));
   }
   ptr += 2;
-  encryptAndSendData(buffer, ptr-buffer);
-  bufp.reset(0);
+  size_t buflen = ptr-buffer.get();
+  encryptAndSendData(buffer.release(), buflen);
 }
 
 // This function reads exactly until the end of VC marker is reached.
@@ -522,10 +520,10 @@ void MSEHandshake::sendReceiverStep2()
   //   cryptoSelect(CRYPTO_BITFIELD_LENGTH bytes),
   //   len(padD)(2bytes),
   //   padD(len(padD)bytes <= MAX_PAD_LENGTH)
-  unsigned char* buffer = new unsigned char
-    [VC_LENGTH+CRYPTO_BITFIELD_LENGTH+2+MAX_PAD_LENGTH];
-  array_ptr<unsigned char> bufp(buffer);
-  unsigned char* ptr = buffer;
+  auto buffer = make_unique<unsigned char[]>(VC_LENGTH+
+                                             CRYPTO_BITFIELD_LENGTH+2+
+                                             MAX_PAD_LENGTH);
+  unsigned char* ptr = buffer.get();
   // VC
   memcpy(ptr, VC, sizeof(VC));
   ptr += sizeof(VC);
@@ -542,8 +540,8 @@ void MSEHandshake::sendReceiverStep2()
   // padD, all zeroed
   memset(ptr, 0, padDLength);
   ptr += padDLength;
-  encryptAndSendData(buffer, ptr-buffer);
-  bufp.reset(0);
+  size_t buflen = ptr - buffer.get();
+  encryptAndSendData(buffer.release(), buflen);
 }
 
 uint16_t MSEHandshake::verifyPadLength(const unsigned char* padlenbuf, const char* padName)
diff --git a/src/MessageDigest.cc b/src/MessageDigest.cc
index 01189c7f..725c56c8 100644
--- a/src/MessageDigest.cc
+++ b/src/MessageDigest.cc
@@ -186,10 +186,9 @@ void MessageDigest::digest(unsigned char* md)
 std::string MessageDigest::digest()
 {
   size_t length = pImpl_->getDigestLength();
-  array_ptr<unsigned char> buf(new unsigned char[length]);
-  pImpl_->digest(buf);
-  std::string hd(&buf[0], &buf[length]);
-  return hd;
+  auto buf = make_unique<unsigned char[]>(length);
+  pImpl_->digest(buf.get());
+  return std::string(&buf[0], &buf[length]);
 }
 
 } // namespace aria2
diff --git a/src/OptionParser.cc b/src/OptionParser.cc
index bf472ba2..bcb900cb 100644
--- a/src/OptionParser.cc
+++ b/src/OptionParser.cc
@@ -152,11 +152,11 @@ void OptionParser::parseArg
   size_t numPublicOption = countPublicOption(handlers_.begin(),
                                              handlers_.end());
   int lopt;
-  array_ptr<struct option> longOpts(new struct option[numPublicOption+1]);
-  putOptions(longOpts, &lopt, handlers_.begin(), handlers_.end());
+  auto longOpts = make_unique<struct option[]>(numPublicOption+1);
+  putOptions(longOpts.get(), &lopt, handlers_.begin(), handlers_.end());
   std::string optstring = createOptstring(handlers_.begin(), handlers_.end());
   while(1) {
-    int c = getopt_long(argc, argv, optstring.c_str(), longOpts, 0);
+    int c = getopt_long(argc, argv, optstring.c_str(), longOpts.get(), 0);
     if(c == -1) {
       break;
     }
diff --git a/src/a2functional.h b/src/a2functional.h
index dc13a443..11391e51 100644
--- a/src/a2functional.h
+++ b/src/a2functional.h
@@ -186,6 +186,12 @@ std::unique_ptr<T> make_unique(U&&... u)
   return std::unique_ptr<T>(new T(std::forward<U>(u)...));
 }
 
+template<typename T>
+std::unique_ptr<T> make_unique(size_t size)
+{
+  return std::unique_ptr<T>(new typename std::remove_extent<T>::type[size]());
+}
+
 } // namespace aria2
 
 #endif // D_A2_FUNCTIONAL_H
diff --git a/src/array_fun.h b/src/array_fun.h
index ed562ed8..b8054c36 100644
--- a/src/array_fun.h
+++ b/src/array_fun.h
@@ -53,45 +53,6 @@ char (&char_array_ref_fun(T (&)[0u]))[0u];
 // To calculate size of array at compile time, we use macro here.
 #define A2_ARRAY_LEN(X) sizeof(char_array_ref_fun(X))
 
-template<typename T>
-class array_ptr {
-private:
-  T* array_;
-
-  // Copies are not allowed. Let's make them private.
-  array_ptr(const array_ptr& s);
-
-  array_ptr& operator=(const array_ptr& s);
-
-  template<typename S>
-  array_ptr& operator=(const array_ptr<S>& s);
-
-public:
-  array_ptr():array_(0) {}
-
-  explicit array_ptr(T* array):array_(array) {}
-
-  ~array_ptr()
-  {
-    delete [] array_;
-  }
-
-  operator T*()
-  {
-    return array_;
-  }
-
-  operator const T*() const
-  {
-    return array_;
-  }
-
-  void reset(T* array)
-  {
-    array_ = array;
-  }
-};
-
 template<typename T, size_t N>
 class array_wrapper {
 private:
diff --git a/src/util.cc b/src/util.cc
index b59fecbc..a671447d 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -129,16 +129,15 @@ int wCharToAnsi(char* out, size_t outLength, const wchar_t* src)
 std::wstring utf8ToWChar(const char* src)
 {
   int len = utf8ToWChar(0, 0, src);
-  if(len == 0) {
+  if(len <= 0) {
     abort();
   }
-  array_ptr<wchar_t> buf(new wchar_t[len]);
-  len = utf8ToWChar(buf, len, src);
-  if(len == 0) {
+  auto buf = make_unique<wchar_t[]>((size_t)len);
+  len = utf8ToWChar(buf.get(), len, src);
+  if(len <= 0) {
     abort();
   } else {
-    std::wstring dest(buf);
-    return dest;
+    return buf.get();
   }
 }
 
@@ -151,47 +150,45 @@ std::string utf8ToNative(const std::string& src)
 {
   std::wstring wsrc = utf8ToWChar(src);
   int len = wCharToAnsi(0, 0, wsrc.c_str());
-  if(len == 0) {
+  if(len <= 0) {
     abort();
   }
-  array_ptr<char> buf(new char[len]);
-  len = wCharToAnsi(buf, len, wsrc.c_str());
-  if(len == 0) {
+  auto buf = make_unique<char[]>((size_t)len);
+  len = wCharToAnsi(buf.get(), len, wsrc.c_str());
+  if(len <= 0) {
     abort();
   } else {
-    std::string dest(buf);
-    return dest;
+    return buf.get();
   }
 }
 
 std::string wCharToUtf8(const std::wstring& wsrc)
 {
   int len = wCharToUtf8(0, 0, wsrc.c_str());
-  if(len == 0) {
+  if(len <= 0) {
     abort();
   }
-  array_ptr<char> buf(new char[len]);
-  len = wCharToUtf8(buf, len, wsrc.c_str());
-  if(len == 0) {
+  auto buf = make_unique<char[]>((size_t)len);
+  len = wCharToUtf8(buf.get(), len, wsrc.c_str());
+  if(len <= 0) {
     abort();
   } else {
-    std::string dest(buf);
-    return dest;
+    return buf.get();
   }
 }
 
 std::string nativeToUtf8(const std::string& src)
 {
   int len = ansiToWChar(0, 0, src.c_str());
-  if(len == 0) {
+  if(len <= 0) {
     abort();
   }
-  array_ptr<wchar_t> buf(new wchar_t[len]);
-  len = ansiToWChar(buf, len, src.c_str());
-  if(len == 0) {
+  auto buf = make_unique<wchar_t[]>((size_t)len);
+  len = ansiToWChar(buf.get(), len, src.c_str());
+  if(len <= 0) {
     abort();
   } else {
-    return wCharToUtf8(std::wstring(buf));
+    return wCharToUtf8(std::wstring(buf.get()));
   }
 }
 #endif // __MINGW32__
@@ -1770,12 +1767,12 @@ void executeHook
   }
   int cmdlineLen = utf8ToWChar(0, 0, cmdline.c_str());
   assert(cmdlineLen > 0);
-  array_ptr<wchar_t> wcharCmdline(new wchar_t[cmdlineLen]);
-  cmdlineLen = utf8ToWChar(wcharCmdline, cmdlineLen, cmdline.c_str());
+  auto wcharCmdline = std::unique_ptr<wchar_t[]>(new wchar_t[cmdlineLen]);
+  cmdlineLen = utf8ToWChar(wcharCmdline.get(), cmdlineLen, cmdline.c_str());
   assert(cmdlineLen > 0);
   A2_LOG_INFO(fmt("Executing user command: %s", cmdline.c_str()));
   DWORD rc = CreateProcessW(batch ? utf8ToWChar(cmdexe).c_str() : NULL,
-                            wcharCmdline,
+                            wcharCmdline.get(),
                             NULL,
                             NULL,
                             true,
diff --git a/test/array_funTest.cc b/test/array_funTest.cc
index 1158d577..ae796c8c 100644
--- a/test/array_funTest.cc
+++ b/test/array_funTest.cc
@@ -11,7 +11,6 @@ class array_funTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testArray_negate);
   CPPUNIT_TEST(testArray_and);
   CPPUNIT_TEST(testArrayLength);
-  CPPUNIT_TEST(testArrayPtr);
   CPPUNIT_TEST(testArrayWrapper);
   CPPUNIT_TEST_SUITE_END();
 
@@ -21,7 +20,6 @@ public:
   void testArray_negate();
   void testArray_and();
   void testArrayLength();
-  void testArrayPtr();
   void testArrayWrapper();
 
   struct X{
@@ -70,15 +68,6 @@ void array_funTest::testArrayLength()
   // CPPUNIT_ASSERT_EQUAL((size_t)0, A2_ARRAY_LEN(zeroLengthArray));
 }
 
-namespace {
-// Check operator[] in const context.
-void arrayPtrConst(const array_ptr<struct array_funTest::X>& ax)
-{
-  CPPUNIT_ASSERT_EQUAL(100, ax[3].m);
-  CPPUNIT_ASSERT_EQUAL(99, ax[2].m);
-}
-} // namespace
-
 namespace {
 void arrayPtrCast(struct array_funTest::X* x) {}
 } // namespace
@@ -87,19 +76,6 @@ namespace {
 void arrayPtrConstCast(const struct array_funTest::X* x) {}
 } // namespace
 
-void array_funTest::testArrayPtr()
-{
-  array_ptr<struct X> ax(new struct X[10]);
-  ax[3].m = 100;
-  ax[2].m = 99;
-  CPPUNIT_ASSERT_EQUAL(100, ax[3].m);
-  CPPUNIT_ASSERT_EQUAL(99, ax[2].m);
-  arrayPtrConst(ax);
-
-  arrayPtrCast(ax);
-  arrayPtrConstCast(ax);
-}
-
 namespace {
 void arrayWrapperConst(const array_wrapper<int, 10>& array)
 {