diff --git a/include/libtorrent/connection_queue.hpp b/include/libtorrent/connection_queue.hpp
index 17be248bf..b3b7cde86 100644
--- a/include/libtorrent/connection_queue.hpp
+++ b/include/libtorrent/connection_queue.hpp
@@ -36,6 +36,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <list>
 #include <boost/function.hpp>
 #include <boost/noncopyable.hpp>
+#include <boost/thread/recursive_mutex.hpp>
 #include "libtorrent/socket.hpp"
 #include "libtorrent/time.hpp"
 
@@ -88,6 +89,10 @@ private:
 	int m_half_open_limit;
 
 	deadline_timer m_timer;
+
+	typedef boost::recursive_mutex mutex_t;
+	mutable mutex_t m_mutex;
+
 #ifndef NDEBUG
 	bool m_in_timeout_function;
 #endif
diff --git a/src/connection_queue.cpp b/src/connection_queue.cpp
index 859205ed0..544ebec6b 100644
--- a/src/connection_queue.cpp
+++ b/src/connection_queue.cpp
@@ -54,6 +54,8 @@ namespace libtorrent
 		, boost::function<void()> const& on_timeout
 		, time_duration timeout)
 	{
+		mutex_t::scoped_lock l(m_mutex);
+
 		INVARIANT_CHECK;
 
 		m_queue.push_back(entry());
@@ -68,6 +70,8 @@ namespace libtorrent
 
 	void connection_queue::done(int ticket)
 	{
+		mutex_t::scoped_lock l(m_mutex);
+
 		INVARIANT_CHECK;
 
 		std::list<entry>::iterator i = std::find_if(m_queue.begin()
@@ -105,6 +109,8 @@ namespace libtorrent
 
 	void connection_queue::try_connect()
 	{
+		mutex_t::scoped_lock l(m_mutex);
+
 		INVARIANT_CHECK;
 
 		if (!free_slots() || m_queue.empty())
@@ -148,6 +154,8 @@ namespace libtorrent
 	
 	void connection_queue::on_timeout(asio::error_code const& e)
 	{
+		mutex_t::scoped_lock l(m_mutex);
+
 		INVARIANT_CHECK;
 #ifndef NDEBUG
 		function_guard guard_(m_in_timeout_function);