diff --git a/include/libtorrent/aux_/session_impl.hpp b/include/libtorrent/aux_/session_impl.hpp
index 3095dbd4b..510a0f857 100644
--- a/include/libtorrent/aux_/session_impl.hpp
+++ b/include/libtorrent/aux_/session_impl.hpp
@@ -313,7 +313,7 @@ namespace libtorrent
 			void dht_get_mutable_item(boost::array<char, 32> key
 				, std::string salt = std::string());
 
-			void dht_put_immutable_item(entry data, sha1_hash target);
+			void dht_put_immutable_item(entry const& data, sha1_hash target);
 
 			void dht_put_mutable_item(boost::array<char, 32> key
 				, boost::function<void(entry&, boost::array<char,64>&
diff --git a/include/libtorrent/kademlia/dht_tracker.hpp b/include/libtorrent/kademlia/dht_tracker.hpp
index b32e82ccd..0f2749db3 100644
--- a/include/libtorrent/kademlia/dht_tracker.hpp
+++ b/include/libtorrent/kademlia/dht_tracker.hpp
@@ -104,14 +104,14 @@ namespace libtorrent { namespace dht
 		// for immutable_item.
 		// the callback function will be called when put operation is done.
 		// the int parameter indicates the success numbers of put operation.
-		void put_item(entry data
+		void put_item(entry const& data
 			, boost::function<void(int)> cb);
 
 		// for mutable_item.
 		// the data_cb will be called when we get authoritative mutable_item,
 		// the cb is same as put immutable_item.
 		void put_item(char const* key
-			, boost::function<void(item&, int)> cb
+			, boost::function<void(item const&, int)> cb
 			, boost::function<void(item&)> data_cb, std::string salt = std::string());
 
 		// send an arbitrary DHT request directly to a node
diff --git a/include/libtorrent/kademlia/get_item.hpp b/include/libtorrent/kademlia/get_item.hpp
index 44ed3980d..00df641c9 100644
--- a/include/libtorrent/kademlia/get_item.hpp
+++ b/include/libtorrent/kademlia/get_item.hpp
@@ -43,7 +43,7 @@ namespace libtorrent { namespace dht
 class get_item : public find_data
 {
 public:
-	typedef boost::function<void(item&, bool)> data_callback;
+	typedef boost::function<void(item const&, bool)> data_callback;
 
 	void got_data(bdecode_node const& v,
 		char const* pk,
diff --git a/include/libtorrent/kademlia/node.hpp b/include/libtorrent/kademlia/node.hpp
index 40e1b2cba..ae18994c1 100644
--- a/include/libtorrent/kademlia/node.hpp
+++ b/include/libtorrent/kademlia/node.hpp
@@ -177,12 +177,12 @@ public:
 	void direct_request(udp::endpoint ep, entry& e
 		, boost::function<void(msg const&)> f);
 
-	void get_item(sha1_hash const& target, boost::function<void(item&)> f);
-	void get_item(char const* pk, std::string const& salt, boost::function<void(item&, bool)> f);
+	void get_item(sha1_hash const& target, boost::function<void(item const&)> f);
+	void get_item(char const* pk, std::string const& salt, boost::function<void(item const&, bool)> f);
 
-	void put_item(sha1_hash const& target, entry& data, boost::function<void(int)> f);
+	void put_item(sha1_hash const& target, entry const& data, boost::function<void(int)> f);
 	void put_item(char const* pk, std::string const& salt
-		, boost::function<void(item&, int)> f
+		, boost::function<void(item const&, int)> f
 		, boost::function<void(item&)> data_cb);
 
 	bool verify_token(std::string const& token, char const* info_hash
diff --git a/include/libtorrent/kademlia/put_data.hpp b/include/libtorrent/kademlia/put_data.hpp
index 23f65b76b..5330581b5 100644
--- a/include/libtorrent/kademlia/put_data.hpp
+++ b/include/libtorrent/kademlia/put_data.hpp
@@ -53,7 +53,7 @@ class node;
 
 struct put_data: traversal_algorithm
 {
-	typedef boost::function<void(item&, int)> put_callback;
+	typedef boost::function<void(item const&, int)> put_callback;
 
 	put_data(node& node, put_callback const& callback);
 
diff --git a/src/kademlia/dht_tracker.cpp b/src/kademlia/dht_tracker.cpp
index b20cc3652..29a511835 100644
--- a/src/kademlia/dht_tracker.cpp
+++ b/src/kademlia/dht_tracker.cpp
@@ -254,7 +254,7 @@ namespace libtorrent { namespace dht
 		m_dht.get_item(key, salt, cb);
 	}
 
-	void dht_tracker::put_item(entry data
+	void dht_tracker::put_item(entry const& data
 		, boost::function<void(int)> cb)
 	{
 		std::string flat_data;
@@ -266,7 +266,7 @@ namespace libtorrent { namespace dht
 	}
 
 	void dht_tracker::put_item(char const* key
-		, boost::function<void(item&, int)> cb
+		, boost::function<void(item const&, int)> cb
 		, boost::function<void(item&)> data_cb, std::string salt)
 	{
 		m_dht.put_item(key, salt, cb, data_cb);
diff --git a/src/kademlia/get_item.cpp b/src/kademlia/get_item.cpp
index 25ca0330b..317b9a151 100644
--- a/src/kademlia/get_item.cpp
+++ b/src/kademlia/get_item.cpp
@@ -119,7 +119,7 @@ get_item::get_item(
 	, nodes_callback const& ncallback)
 	: find_data(dht_node, item_target_id(
 		std::make_pair(salt.c_str(), int(salt.size())), pk)
-	        , ncallback)
+		, ncallback)
 	, m_data_callback(dcallback)
 	, m_data(pk, salt)
 	, m_immutable(false)
diff --git a/src/kademlia/node.cpp b/src/kademlia/node.cpp
index cb06b59c6..e4491e058 100644
--- a/src/kademlia/node.cpp
+++ b/src/kademlia/node.cpp
@@ -423,7 +423,7 @@ void node::direct_request(udp::endpoint ep, entry& e
 }
 
 void node::get_item(sha1_hash const& target
-	, boost::function<void(item&)> f)
+	, boost::function<void(item const&)> f)
 {
 #ifndef TORRENT_DISABLE_LOGGING
 	if (m_observer)
@@ -441,7 +441,7 @@ void node::get_item(sha1_hash const& target
 }
 
 void node::get_item(char const* pk, std::string const& salt
-	, boost::function<void(item&, bool)> f)
+	, boost::function<void(item const&, bool)> f)
 {
 #ifndef TORRENT_DISABLE_LOGGING
 	if (m_observer)
@@ -462,13 +462,13 @@ namespace {
 void put(std::vector<std::pair<node_entry, std::string> > const& nodes
 	, boost::intrusive_ptr<dht::put_data> ta)
 {
-    ta->set_targets(nodes);
+	ta->set_targets(nodes);
 	ta->start();
 }
 
-void put_data_cb(item& i, bool auth
-		, boost::intrusive_ptr<put_data> ta
-		, boost::function<void(item&)> f)
+void put_data_cb(item i, bool auth
+	, boost::intrusive_ptr<put_data> ta
+	, boost::function<void(item&)> f)
 {
 	// call data_callback only when we got authoritative data.
 	if (auth)
@@ -480,7 +480,7 @@ void put_data_cb(item& i, bool auth
 
 } // namespace
 
-void node::put_item(sha1_hash const& target, entry& data, boost::function<void(int)> f)
+void node::put_item(sha1_hash const& target, entry const& data, boost::function<void(int)> f)
 {
 #ifndef TORRENT_DISABLE_LOGGING
 	if (m_observer)
@@ -505,7 +505,7 @@ void node::put_item(sha1_hash const& target, entry& data, boost::function<void(i
 }
 
 void node::put_item(char const* pk, std::string const& salt
-	, boost::function<void(item&, int)> f
+	, boost::function<void(item const&, int)> f
 	, boost::function<void(item&)> data_cb)
 {
 	#ifndef TORRENT_DISABLE_LOGGING
diff --git a/src/kademlia/put_data.cpp b/src/kademlia/put_data.cpp
index f23f09673..51e7b4556 100644
--- a/src/kademlia/put_data.cpp
+++ b/src/kademlia/put_data.cpp
@@ -67,7 +67,6 @@ void put_data::set_targets(std::vector<std::pair<node_entry, std::string> > cons
 
 void put_data::done()
 {
-	if (m_invoke_count != 0) return;
 	m_done = true;
 
 #ifndef TORRENT_DISABLE_LOGGING
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index c970c131a..03fd963b5 100644
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -5654,7 +5654,7 @@ retry:
 				alerts.emplace_alert<dht_put_alert>(target, num);
 		}
 
-		void on_dht_put_mutable_item(alert_manager& alerts, dht::item& i, int num)
+		void on_dht_put_mutable_item(alert_manager& alerts, dht::item const& i, int num)
 		{
 			boost::array<char, 64> sig = i.sig();
 			boost::array<char, 32> pk = i.pk();
@@ -5694,7 +5694,7 @@ retry:
 
 	} // anonymous namespace
 
-	void session_impl::dht_put_immutable_item(entry data, sha1_hash target)
+	void session_impl::dht_put_immutable_item(entry const& data, sha1_hash target)
 	{
 		if (!m_dht) return;
 		m_dht->put_item(data, boost::bind(&on_dht_put_immutable_item, boost::ref(m_alerts)
diff --git a/test/test_dht.cpp b/test/test_dht.cpp
index 6a8ce602d..1d5d2d108 100644
--- a/test/test_dht.cpp
+++ b/test/test_dht.cpp
@@ -481,7 +481,7 @@ std::vector<dht::item> g_got_items;
 dht::item g_put_item;
 int g_put_count;
 
-void get_mutable_item_cb(dht::item& i, bool a)
+void get_mutable_item_cb(dht::item const& i, bool a)
 {
 	if (!a) return;
 	if (!i.empty())
@@ -498,12 +498,12 @@ void put_mutable_item_data_cb(dht::item& i)
 	g_put_count++;
 }
 
-void put_mutable_item_cb(dht::item&, int num, int expect)
+void put_mutable_item_cb(dht::item const&, int num, int expect)
 {
 	TEST_EQUAL(num, expect);
 }
 
-void get_immutable_item_cb(dht::item& i)
+void get_immutable_item_cb(dht::item const& i)
 {
 	if (!i.empty())
 		g_got_items.push_back(i);