diff --git a/sys/netinet/in_pcb.c b/sys/netinet/in_pcb.c
--- a/sys/netinet/in_pcb.c
+++ b/sys/netinet/in_pcb.c
@@ -1736,7 +1736,7 @@
 #endif
 	inp->inp_flags |= INP_FREED;
 	inp->inp_socket->so_pcb = NULL;
-	inp->inp_socket = NULL;
+	DEBUG_POISON_POINTER(inp->inp_socket);
 
 	RO_INVALIDATE_CACHE(&inp->inp_route);
 #ifdef MAC
@@ -1749,12 +1749,16 @@
 #ifdef INET
 	if (inp->inp_options)
 		(void)m_free(inp->inp_options);
+	DEBUG_POISON_POINTER(inp->inp_options);
 	imo = inp->inp_moptions;
+	DEBUG_POISON_POINTER(inp->inp_moptions);
 #endif
 #ifdef INET6
 	if (inp->inp_vflag & INP_IPV6PROTO) {
 		ip6_freepcbopts(inp->in6p_outputopts);
+		DEBUG_POISON_POINTER(inp->in6p_outputopts);
 		im6o = inp->in6p_moptions;
+		DEBUG_POISON_POINTER(inp->in6p_moptions);
 	} else
 		im6o = NULL;
 #endif