diff --git a/src/socket_base.hpp b/src/socket_base.hpp
index 5a0d9540..fcac9574 100644
--- a/src/socket_base.hpp
+++ b/src/socket_base.hpp
@@ -120,16 +120,16 @@ namespace zmq
         void set_fd(fd_t fd_);
         fd_t fd();
 
-        void event_connected (const std::string &addr_, int fd_);
+        void event_connected (const std::string &addr_, zmq::fd_t fd_);
         void event_connect_delayed (const std::string &addr_, int err_);
         void event_connect_retried (const std::string &addr_, int interval_);
-        void event_listening (const std::string &addr_, int fd_);
+        void event_listening (const std::string &addr_, zmq::fd_t fd_);
         void event_bind_failed (const std::string &addr_, int err_);
-        void event_accepted (const std::string &addr_, int fd_);
+        void event_accepted (const std::string &addr_, zmq::fd_t fd_);
         void event_accept_failed (const std::string &addr_, int err_);
-        void event_closed (const std::string &addr_, int fd_);
-        void event_close_failed (const std::string &addr_, int fd_);
-        void event_disconnected (const std::string &addr_, int fd_);
+        void event_closed (const std::string &addr_, zmq::fd_t fd_);
+        void event_close_failed (const std::string &addr_, int err_);
+        void event_disconnected (const std::string &addr_, zmq::fd_t fd_);
 
     protected: