diff --git a/libp2p/NodeTable.cpp b/libp2p/NodeTable.cpp
index 912754c39..7fe531762 100644
--- a/libp2p/NodeTable.cpp
+++ b/libp2p/NodeTable.cpp
@@ -578,3 +578,29 @@ void NodeTable::doRefreshBuckets(boost::system::error_code const& _ec)
 	m_bucketRefreshTimer.async_wait(runcb);
 }
 
+void PingNode::streamRLP(RLPStream& _s) const
+{
+	_s.appendList(4);
+	_s << dev::p2p::c_protocolVersion << ipAddress << port << expiration;
+}
+
+void PingNode::interpretRLP(bytesConstRef _bytes)
+{
+	RLP r(_bytes);
+	if (r.itemCountStrict() == 3)
+	{
+		version = 2;
+		ipAddress = r[0].toString();
+		port = r[1].toInt<unsigned>(RLP::Strict);
+		expiration = r[2].toInt<unsigned>(RLP::Strict);
+	}
+	else if (r.itemCountStrict() == 4)
+	{
+		version = r[0].toInt<unsigned>(RLP::Strict);
+		ipAddress = r[1].toString();
+		port = r[2].toInt<unsigned>(RLP::Strict);
+		expiration = r[3].toInt<unsigned>(RLP::Strict);
+	}
+	else
+		BOOST_THROW_EXCEPTION(InvalidRLP());
+}
diff --git a/libp2p/NodeTable.h b/libp2p/NodeTable.h
index 655ce7d43..6a167930d 100644
--- a/libp2p/NodeTable.h
+++ b/libp2p/NodeTable.h
@@ -288,6 +288,8 @@ inline std::ostream& operator<<(std::ostream& _out, NodeTable const& _nodeTable)
 	return _out;
 }
 
+struct InvalidRLP: public Exception {};
+
 /**
  * Ping packet: Sent to check if node is alive.
  * PingNode is cached and regenerated after expiration - t, where t is timeout.
@@ -321,8 +323,8 @@ struct PingNode: RLPXDatagram<PingNode>
 	unsigned port;
 	unsigned expiration;
 
-	void streamRLP(RLPStream& _s) const { _s.appendList(4); _s << dev::p2p::c_protocolVersion << ipAddress << port << expiration; }
-	void interpretRLP(bytesConstRef _bytes) { RLP r(_bytes); version = r[0].toInt<unsigned>(); ipAddress = r[1].toString(); port = r[2].toInt<unsigned>(); expiration = r[3].toInt<unsigned>(); }
+	void streamRLP(RLPStream& _s) const override;
+	void interpretRLP(bytesConstRef _bytes) override;
 };
 
 /**