diff --git a/event-old.h b/event-old.h
index 98d3344..b920e68 100644
--- a/event-old.h
+++ b/event-old.h
@@ -2,6 +2,7 @@
 #define __EVENT_OLD_H__
 
 #include <assert.h>
+#include <stdlib.h>
 
 #define BEV_EVENT_READ EVBUFFER_READ
 #define BEV_EVENT_WRITE EVBUFFER_WRITE
@@ -40,4 +41,8 @@ static struct bufferevent *bufferevent_socket_new (struct event_base *base, int
   bufferevent_base_set (base, bev);
   return bev;
 }
+
+static inline void *event_get_callback_arg(const struct event *ev) {
+  return ev->ev_arg;
+}
 #endif