diff --git a/src/openvpn/event.h b/src/openvpn/event.h
index b3ba183bd5e..c212e0705d7 100644
--- a/src/openvpn/event.h
+++ b/src/openvpn/event.h
@@ -82,6 +82,12 @@
 #define EVENT_METHOD_US_TIMEOUT   (1<<0)
 #define EVENT_METHOD_FAST         (1<<1)
 
+/*
+ * The following constant is used as boundary between integer value
+ * and real addresses when passing arguments to event handlers as (void *)
+ */
+#define MULTI_N           ((void *)16) /* upper bound on MTCP_x */
+
 #ifdef _WIN32
 
 typedef const struct rw_handle *event_t;
diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
index 66e5be1b3fc..d50b24c65b5 100644
--- a/src/openvpn/forward.c
+++ b/src/openvpn/forward.c
@@ -2183,7 +2183,8 @@ io_wait_dowork(struct context *c, const unsigned int flags)
     /*
      * Configure event wait based on socket, tuntap flags.
      */
-    socket_set(c->c2.link_socket, c->c2.event_set, socket, (void *)socket_shift, NULL);
+    socket_set(c->c2.link_socket, c->c2.event_set, socket,
+               &c->c2.link_socket->ev_arg, NULL);
     tun_set(c->c1.tuntap, c->c2.event_set, tuntap, (void *)tun_shift, NULL);
 #if defined(TARGET_LINUX) || defined(TARGET_FREEBSD)
     if (socket & EVENT_READ && c->c2.did_open_tun)
@@ -2246,7 +2247,27 @@ io_wait_dowork(struct context *c, const unsigned int flags)
                 for (i = 0; i < status; ++i)
                 {
                     const struct event_set_return *e = &esr[i];
-                    c->c2.event_set_status |= ((e->rwflags & 3) << (uintptr_t)e->arg);
+                    uintptr_t shift;
+
+                    if (e->arg >= MULTI_N)
+                    {
+                        struct event_arg *ev_arg = (struct event_arg *)e->arg;
+                        if (ev_arg->type != EVENT_ARG_LINK_SOCKET)
+                        {
+                            c->c2.event_set_status = ES_ERROR;
+                            msg(D_LINK_ERRORS,
+                                "io_work: non socket event delivered");
+                            return;
+                        }
+
+                        shift = socket_shift;
+                    }
+                    else
+                    {
+                        shift = (uintptr_t)e->arg;
+                    }
+
+                    c->c2.event_set_status |= ((e->rwflags & 3) << shift);
                 }
             }
             else if (status == 0)
diff --git a/src/openvpn/mtcp.c b/src/openvpn/mtcp.c
index 28f6e8ef626..a2841f0da33 100644
--- a/src/openvpn/mtcp.c
+++ b/src/openvpn/mtcp.c
@@ -60,7 +60,13 @@
 #define MTCP_FILE_CLOSE_WRITE ((void *)5)
 #define MTCP_DCO        ((void *)6)
 
-#define MTCP_N           ((void *)16) /* upper bound on MTCP_x */
+struct ta_iow_flags
+{
+    unsigned int flags;
+    unsigned int ret;
+    unsigned int tun;
+    unsigned int sock;
+};
 
 #ifdef ENABLE_DEBUG
 static const char *
@@ -686,7 +692,7 @@ multi_tcp_process_io(struct multi_context *m)
         struct event_set_return *e = &mtcp->esr[i];
 
         /* incoming data for instance or listening socket? */
-        if (e->arg >= MTCP_N)
+        if (e->arg >= MULTI_N)
         {
             struct event_arg *ev_arg = (struct event_arg *)e->arg;
             switch (ev_arg->type)