diff --git a/libi2pd/SSU2.cpp b/libi2pd/SSU2.cpp
index d2cb1a26..5bb27a40 100644
--- a/libi2pd/SSU2.cpp
+++ b/libi2pd/SSU2.cpp
@@ -851,6 +851,7 @@ namespace transport
 			
 			m_PacketsPool.CleanUpMt ();
 			m_SentPacketsPool.CleanUp ();
+			m_IncompleteMessagesPool.CleanUp ();
 			m_FragmentsPool.CleanUp ();
 			ScheduleCleanup ();
 		}	
diff --git a/libi2pd/SSU2.h b/libi2pd/SSU2.h
index 68d507ca..8b755f60 100644
--- a/libi2pd/SSU2.h
+++ b/libi2pd/SSU2.h
@@ -98,8 +98,9 @@ namespace transport
 			void RescheduleIntroducersUpdateTimerV6 ();
 
 			i2p::util::MemoryPool<SSU2SentPacket>& GetSentPacketsPool () { return m_SentPacketsPool; };
+			i2p::util::MemoryPool<SSU2IncompleteMessage>& GetIncompleteMessagesPool () { return m_IncompleteMessagesPool; };
 			i2p::util::MemoryPool<SSU2IncompleteMessage::Fragment>& GetFragmentsPool () { return m_FragmentsPool; };
-		
+					
 		private:
 
 			boost::asio::ip::udp::socket& OpenSocket (const boost::asio::ip::udp::endpoint& localEndpoint);
@@ -152,6 +153,7 @@ namespace transport
 			std::list<i2p::data::IdentHash> m_Introducers, m_IntroducersV6; // introducers we are connected to
 			i2p::util::MemoryPoolMt<Packet> m_PacketsPool;
 			i2p::util::MemoryPool<SSU2SentPacket> m_SentPacketsPool;
+			i2p::util::MemoryPool<SSU2IncompleteMessage> m_IncompleteMessagesPool;
 			i2p::util::MemoryPool<SSU2IncompleteMessage::Fragment> m_FragmentsPool;
 			boost::asio::deadline_timer m_TerminationTimer, m_CleanupTimer, m_ResendTimer,
 				m_IntroducersUpdateTimer, m_IntroducersUpdateTimerV6;
diff --git a/libi2pd/SSU2Session.cpp b/libi2pd/SSU2Session.cpp
index 0f53bf7b..5e97b461 100644
--- a/libi2pd/SSU2Session.cpp
+++ b/libi2pd/SSU2Session.cpp
@@ -1772,7 +1772,7 @@ namespace transport
 		}
 		else
 		{
-			m = std::make_shared<SSU2IncompleteMessage>();
+			m = m_Server.GetIncompleteMessagesPool ().AcquireShared ();
 			m_IncompleteMessages.emplace (msgID, m);
 		}
 		m->msg = msg;
@@ -1791,11 +1791,17 @@ namespace transport
 	{
 		if (len < 5) return;
 		uint8_t fragmentNum = buf[0] >> 1;
+		if (!fragmentNum || fragmentNum >= SSU2_MAX_NUM_FRAGMENTS)
+		{
+			LogPrint (eLogWarning, "SSU2: Invalid follow-on fragment num ", fragmentNum);
+			return;
+		}	
 		bool isLast = buf[0] & 0x01;
 		uint32_t msgID; memcpy (&msgID, buf + 1, 4);
 		auto it = m_IncompleteMessages.find (msgID);
 		if (it != m_IncompleteMessages.end ())
 		{
+			if (fragmentNum < it->second->nextFragmentNum) return; // duplicate
 			if (it->second->nextFragmentNum == fragmentNum && fragmentNum < SSU2_MAX_NUM_FRAGMENTS &&
 			    it->second->msg)
 			{
@@ -1823,16 +1829,11 @@ namespace transport
 		else
 		{
 			// follow-on fragment before first fragment
-			auto msg = std::make_shared<SSU2IncompleteMessage> ();
+			auto msg = m_Server.GetIncompleteMessagesPool ().AcquireShared ();
 			msg->nextFragmentNum = 0;
 			it = m_IncompleteMessages.emplace (msgID, msg).first;
 		}
 		// insert out of sequence fragment
-		if (fragmentNum >= SSU2_MAX_NUM_FRAGMENTS)
-		{
-			LogPrint (eLogWarning, "SSU2: Fragment number ", fragmentNum, " exceeds ", SSU2_MAX_NUM_FRAGMENTS);
-			return;
-		}
 		auto fragment = m_Server.GetFragmentsPool ().AcquireShared ();
 		memcpy (fragment->buf, buf + 5, len -5);
 		fragment->len = len - 5;
diff --git a/libi2pd/SSU2Session.h b/libi2pd/SSU2Session.h
index 08a4b7cf..ef9ab573 100644
--- a/libi2pd/SSU2Session.h
+++ b/libi2pd/SSU2Session.h
@@ -345,7 +345,7 @@ namespace transport
 			uint32_t m_SendPacketNum, m_ReceivePacketNum;
 			std::set<uint32_t> m_OutOfSequencePackets; // packet nums > receive packet num
 			std::map<uint32_t, std::shared_ptr<SSU2SentPacket> > m_SentPackets; // packetNum -> packet
-			std::map<uint32_t, std::shared_ptr<SSU2IncompleteMessage> > m_IncompleteMessages; // I2NP
+			std::unordered_map<uint32_t, std::shared_ptr<SSU2IncompleteMessage> > m_IncompleteMessages; // msgID -> I2NP
 			std::map<uint32_t, std::pair <std::shared_ptr<SSU2Session>, uint64_t > > m_RelaySessions; // nonce->(Alice, timestamp) for Bob or nonce->(Charlie, timestamp) for Alice
 			std::map<uint32_t, std::pair <std::shared_ptr<SSU2Session>, uint64_t > > m_PeerTests; // same as for relay sessions
 			std::list<std::shared_ptr<I2NPMessage> > m_SendQueue;