diff --git a/rai/core_test/rpc.cpp b/rai/core_test/rpc.cpp
index 4ef488b1..f6cc4050 100644
--- a/rai/core_test/rpc.cpp
+++ b/rai/core_test/rpc.cpp
@@ -2711,7 +2711,7 @@ TEST (rpc, account_info)
 	std::string balance (response.json.get<std::string> ("balance"));
 	ASSERT_EQ ("100", balance);
 	std::string modified_timestamp (response.json.get<std::string> ("modified_timestamp"));
-	ASSERT_TRUE (abs (time - stol (modified_timestamp)) < 5);
+	ASSERT_TRUE (std::abs (time - stol (modified_timestamp)) < 5);
 	std::string block_count (response.json.get<std::string> ("block_count"));
 	ASSERT_EQ ("2", block_count);
 }
@@ -3087,4 +3087,4 @@ TEST (rpc, wallet_create_fail)
 		system.poll ();
 	}
 	ASSERT_EQ ("Failed to create wallet. Increase lmdb_max_dbs in node config.", response.json.get<std::string> ("error"));
-}
\ No newline at end of file
+}
diff --git a/rai/lib/blocks.cpp b/rai/lib/blocks.cpp
index fb5ff3ec..e82a9eb5 100644
--- a/rai/lib/blocks.cpp
+++ b/rai/lib/blocks.cpp
@@ -37,6 +37,10 @@ bool rai::from_string_hex (std::string const & value_a, uint64_t & target_a)
 	return result;
 }
 
+rai::block::~block ()
+{
+}
+
 std::string rai::block::to_json ()
 {
 	std::string result;
@@ -1112,3 +1116,23 @@ void rai::receive_hashables::hash (blake2b_state & hash_a) const
 	blake2b_update (&hash_a, previous.bytes.data (), sizeof (previous.bytes));
 	blake2b_update (&hash_a, source.bytes.data (), sizeof (source.bytes));
 }
+
+rai::block_visitor::~block_visitor ()
+{
+}
+
+rai::open_block::~open_block ()
+{
+}
+
+rai::change_block::~change_block ()
+{
+}
+
+rai::send_block::~send_block ()
+{
+}
+
+rai::receive_block::~receive_block ()
+{
+}
diff --git a/rai/lib/blocks.hpp b/rai/lib/blocks.hpp
index 637cac0b..3d5ec776 100644
--- a/rai/lib/blocks.hpp
+++ b/rai/lib/blocks.hpp
@@ -60,6 +60,7 @@ public:
 	virtual bool operator== (rai::block const &) const = 0;
 	virtual rai::block_type type () const = 0;
 	virtual void signature_set (rai::uint512_union const &) = 0;
+	virtual ~block ();
 };
 class send_hashables
 {
@@ -78,6 +79,7 @@ public:
 	send_block (rai::block_hash const &, rai::account const &, rai::amount const &, rai::raw_key const &, rai::public_key const &, uint64_t);
 	send_block (bool &, rai::stream &);
 	send_block (bool &, boost::property_tree::ptree const &);
+	virtual ~send_block ();
 	using rai::block::hash;
 	void hash (blake2b_state &) const override;
 	uint64_t block_work () const override;
@@ -116,6 +118,7 @@ public:
 	receive_block (rai::block_hash const &, rai::block_hash const &, rai::raw_key const &, rai::public_key const &, uint64_t);
 	receive_block (bool &, rai::stream &);
 	receive_block (bool &, boost::property_tree::ptree const &);
+	virtual ~receive_block ();
 	using rai::block::hash;
 	void hash (blake2b_state &) const override;
 	uint64_t block_work () const override;
@@ -156,6 +159,7 @@ public:
 	open_block (rai::block_hash const &, rai::account const &, rai::account const &, std::nullptr_t);
 	open_block (bool &, rai::stream &);
 	open_block (bool &, boost::property_tree::ptree const &);
+	virtual ~open_block ();
 	using rai::block::hash;
 	void hash (blake2b_state &) const override;
 	uint64_t block_work () const override;
@@ -194,6 +198,7 @@ public:
 	change_block (rai::block_hash const &, rai::account const &, rai::raw_key const &, rai::public_key const &, uint64_t);
 	change_block (bool &, rai::stream &);
 	change_block (bool &, boost::property_tree::ptree const &);
+	virtual ~change_block ();
 	using rai::block::hash;
 	void hash (blake2b_state &) const override;
 	uint64_t block_work () const override;
@@ -223,6 +228,7 @@ public:
 	virtual void receive_block (rai::receive_block const &) = 0;
 	virtual void open_block (rai::open_block const &) = 0;
 	virtual void change_block (rai::change_block const &) = 0;
+	virtual ~block_visitor ();
 };
 std::unique_ptr<rai::block> deserialize_block (rai::stream &);
 std::unique_ptr<rai::block> deserialize_block (rai::stream &, rai::block_type);
diff --git a/rai/node/bootstrap.cpp b/rai/node/bootstrap.cpp
index 7124f93c..6358b4c9 100644
--- a/rai/node/bootstrap.cpp
+++ b/rai/node/bootstrap.cpp
@@ -25,6 +25,9 @@ public:
 	complete (true)
 	{
 	}
+	virtual ~add_dependency_visitor ()
+	{
+	}
 	void send_block (rai::send_block const & block_a) override
 	{
 		add_dependency (block_a.hashables.previous);
@@ -127,6 +130,10 @@ node (node_a)
 {
 }
 
+rai::push_synchronization::~push_synchronization ()
+{
+}
+
 bool rai::push_synchronization::synchronized (MDB_txn * transaction_a, rai::block_hash const & hash_a)
 {
 	auto result (!node.store.unsynced_exists (transaction_a, hash_a));
@@ -1368,6 +1375,9 @@ public:
 	connection (connection_a)
 	{
 	}
+	virtual ~request_response_visitor ()
+	{
+	}
 	void keepalive (rai::keepalive const &) override
 	{
 		assert (false);
diff --git a/rai/node/bootstrap.hpp b/rai/node/bootstrap.hpp
index e3b80dc2..56baa0c1 100644
--- a/rai/node/bootstrap.hpp
+++ b/rai/node/bootstrap.hpp
@@ -25,7 +25,7 @@ class block_synchronization
 {
 public:
 	block_synchronization (boost::log::sources::logger_mt &);
-	~block_synchronization ();
+	virtual ~block_synchronization ();
 	// Return true if target already has block
 	virtual bool synchronized (MDB_txn *, rai::block_hash const &) = 0;
 	virtual std::unique_ptr<rai::block> retrieve (MDB_txn *, rai::block_hash const &) = 0;
@@ -42,6 +42,7 @@ class push_synchronization : public rai::block_synchronization
 {
 public:
 	push_synchronization (rai::node &, std::function<rai::sync_result (MDB_txn *, rai::block const &)> const &);
+	virtual ~push_synchronization ();
 	bool synchronized (MDB_txn *, rai::block_hash const &) override;
 	std::unique_ptr<rai::block> retrieve (MDB_txn *, rai::block_hash const &) override;
 	rai::sync_result target (MDB_txn *, rai::block const &) override;
diff --git a/rai/node/common.cpp b/rai/node/common.cpp
index 6e9c47eb..e20a6824 100644
--- a/rai/node/common.cpp
+++ b/rai/node/common.cpp
@@ -518,3 +518,7 @@ void rai::bulk_push::visit (rai::message_visitor & visitor_a) const
 {
 	visitor_a.bulk_push (*this);
 }
+
+rai::message_visitor::~message_visitor ()
+{
+}
diff --git a/rai/node/common.hpp b/rai/node/common.hpp
index 993f3f74..3e3bb9da 100644
--- a/rai/node/common.hpp
+++ b/rai/node/common.hpp
@@ -219,5 +219,6 @@ public:
 	virtual void bulk_pull (rai::bulk_pull const &) = 0;
 	virtual void bulk_push (rai::bulk_push const &) = 0;
 	virtual void frontier_req (rai::frontier_req const &) = 0;
+	virtual ~message_visitor ();
 };
 }
diff --git a/rai/node/node.cpp b/rai/node/node.cpp
index 6a37a1cf..767e050b 100644
--- a/rai/node/node.cpp
+++ b/rai/node/node.cpp
@@ -332,6 +332,9 @@ public:
 	sender (sender_a)
 	{
 	}
+	virtual ~network_message_visitor ()
+	{
+	}
 	void keepalive (rai::keepalive const & message_a) override
 	{
 		if (node.config.logging.network_keepalive_logging ())
@@ -2226,6 +2229,9 @@ public:
 	block (block_a)
 	{
 	}
+	virtual ~confirmed_visitor ()
+	{
+	}
 	void send_block (rai::send_block const & block_a) override
 	{
 		for (auto i (node.wallets.items.begin ()), n (node.wallets.items.end ()); i != n; ++i)
diff --git a/rai/node/rpc.cpp b/rai/node/rpc.cpp
index 57b4f1cf..df26fd0e 100644
--- a/rai/node/rpc.cpp
+++ b/rai/node/rpc.cpp
@@ -1546,6 +1546,9 @@ public:
 	hash (hash_a)
 	{
 	}
+	virtual ~history_visitor ()
+	{
+	}
 	void send_block (rai::send_block const & block_a)
 	{
 		tree.put ("type", "send");
diff --git a/rai/secure.cpp b/rai/secure.cpp
index da44ba87..d9559573 100644
--- a/rai/secure.cpp
+++ b/rai/secure.cpp
@@ -593,6 +593,9 @@ public:
 	result (0)
 	{
 	}
+	virtual ~representative_visitor ()
+	{
+	}
 	void compute (rai::block_hash const & hash_a)
 	{
 		current = hash_a;
@@ -798,6 +801,9 @@ public:
 	store (store_a)
 	{
 	}
+	virtual ~set_predecessor ()
+	{
+	}
 	void fill_value (rai::block const & block_a)
 	{
 		auto hash (block_a.hash ());
@@ -1724,6 +1730,9 @@ public:
 	store (store_a)
 	{
 	}
+	virtual ~root_visitor ()
+	{
+	}
 	void send_block (rai::send_block const & block_a) override
 	{
 		result = block_a.previous ();
@@ -1788,6 +1797,7 @@ class ledger_processor : public rai::block_visitor
 {
 public:
 	ledger_processor (rai::ledger &, MDB_txn *);
+	virtual ~ledger_processor ();
 	void send_block (rai::send_block const &) override;
 	void receive_block (rai::receive_block const &) override;
 	void open_block (rai::open_block const &) override;
@@ -1802,6 +1812,7 @@ class amount_visitor : public rai::block_visitor
 {
 public:
 	amount_visitor (MDB_txn *, rai::block_store &);
+	virtual ~amount_visitor ();
 	void compute (rai::block_hash const &);
 	void send_block (rai::send_block const &) override;
 	void receive_block (rai::receive_block const &) override;
@@ -1818,6 +1829,7 @@ class balance_visitor : public rai::block_visitor
 {
 public:
 	balance_visitor (MDB_txn *, rai::block_store &);
+	virtual ~balance_visitor ();
 	void compute (rai::block_hash const &);
 	void send_block (rai::send_block const &) override;
 	void receive_block (rai::receive_block const &) override;
@@ -1835,6 +1847,10 @@ store (store_a)
 {
 }
 
+amount_visitor::~amount_visitor ()
+{
+}
+
 void amount_visitor::send_block (rai::send_block const & block_a)
 {
 	balance_visitor prev (transaction, store);
@@ -1879,6 +1895,10 @@ result (0)
 {
 }
 
+balance_visitor::~balance_visitor ()
+{
+}
+
 void balance_visitor::send_block (rai::send_block const & block_a)
 {
 	result += block_a.hashables.balance.number ();
@@ -1933,6 +1953,9 @@ public:
 	ledger (ledger_a)
 	{
 	}
+	virtual ~rollback_visitor ()
+	{
+	}
 	void send_block (rai::send_block const & block_a) override
 	{
 		auto hash (block_a.hash ());
@@ -2520,6 +2543,10 @@ transaction (transaction_a)
 {
 }
 
+ledger_processor::~ledger_processor ()
+{
+}
+
 rai::vote::vote (rai::vote const & other_a) :
 sequence (other_a.sequence),
 block (other_a.block),