diff --git a/include/numeric.h b/include/numeric.h
index d92894f1..8ec528cb 100644
--- a/include/numeric.h
+++ b/include/numeric.h
@@ -165,6 +165,7 @@ extern const char *form_str(int);
 #define RPL_NOTOPIC          331
 #define RPL_TOPIC            332
 #define RPL_TOPICWHOTIME     333
+#define RPL_WHOISTEXT        337
 #define RPL_WHOISACTUALLY    338
 
 #define RPL_INVITING         341
diff --git a/modules/m_whois.c b/modules/m_whois.c
index f4fb8854..102a0836 100644
--- a/modules/m_whois.c
+++ b/modules/m_whois.c
@@ -43,6 +43,7 @@
 #include "modules.h"
 #include "hook.h"
 #include "s_newconf.h"
+#include "ipv4_from_ipv6.h"
 
 static void do_whois(struct Client *client_p, struct Client *source_p, int parc, const char *parv[]);
 static void single_whois(struct Client *source_p, struct Client *target_p, int operspy);
@@ -239,6 +240,9 @@ single_whois(struct Client *source_p, struct Client *target_p, int operspy)
 	hook_data_client hdata;
 	int visible;
 	int extra_space = 0;
+#ifdef RB_IPV6
+	struct sockaddr_in ip4;
+#endif
 
 	if(target_p->user == NULL)
 	{
@@ -345,6 +349,20 @@ single_whois(struct Client *source_p, struct Client *target_p, int operspy)
 					   form_str(RPL_WHOISACTUALLY),
 					   target_p->name, target_p->sockhost);
 
+#ifdef RB_IPV6
+		if (target_p->localClient->ip.ss_family == AF_INET6 &&
+				(show_ip(source_p, target_p) ||
+				 (source_p == target_p && !IsIPSpoof(target_p))) &&
+				ipv4_from_ipv6((struct sockaddr_in6 *)&target_p->localClient->ip, &ip4))
+		{
+			rb_inet_ntop_sock((struct sockaddr *)&ip4,
+					buf, sizeof buf);
+			sendto_one_numeric(source_p, RPL_WHOISTEXT,
+					"%s :Underlying IPv4 is %s",
+					target_p->name, buf);
+		}
+#endif /* RB_IPV6 */
+
 		sendto_one_numeric(source_p, RPL_WHOISIDLE, form_str(RPL_WHOISIDLE),
 				   target_p->name, 
 				   rb_current_time() - target_p->localClient->last, 
diff --git a/src/messages.tab b/src/messages.tab
index 72dff03f..0843292d 100644
--- a/src/messages.tab
+++ b/src/messages.tab
@@ -358,7 +358,7 @@ static  const char *  replies[] = {
 /* 334 */       NULL,
 /* 335 */       NULL,
 /* 336 */       NULL,
-/* 337 */       NULL,
+/* 337 RPL_WHOISTEXT, */	"%s :%s",
 /* 338 RPL_WHOISACTUALLY, */	"%s %s :actually using host",
 /* 339 */       NULL,
 /* 340 */       NULL,