diff --git a/websocketpp/transport/asio/endpoint.hpp b/websocketpp/transport/asio/endpoint.hpp
index 9464ced357..9ce58256b0 100644
--- a/websocketpp/transport/asio/endpoint.hpp
+++ b/websocketpp/transport/asio/endpoint.hpp
@@ -87,7 +87,8 @@ public:
 
     // generate and manage our own io_service
     explicit endpoint()
-      : m_external_io_service(false)
+      : m_io_service(NULL)
+      , m_external_io_service(false)
       , m_listen_backlog(0)
       , m_reuse_addr(false)
       , m_state(UNINITIALIZED)