diff -ur orig/linux-2.5.75/net/ipv6/sit.c linux-2.5.75/net/ipv6/sit.c
--- orig/linux-2.5.75/net/ipv6/sit.c	2003-07-10 23:14:48.000000000 +0300
+++ linux-2.5.75/net/ipv6/sit.c	2003-07-12 10:00:27.000000000 +0300
@@ -472,10 +472,13 @@
 			addr_type = ipv6_addr_type(addr6);
 		}
 
-		if ((addr_type & IPV6_ADDR_COMPATv4) == 0)
-			goto tx_error_icmp;
+		if (addr_type & IPV6_ADDR_COMPATv4)
+			dst = addr6->s6_addr32[3];
+		else
+			dst = try_6to4(addr6);
 
-		dst = addr6->s6_addr32[3];
+		if (!dst)
+			goto tx_error_icmp;
 	}
 
 	{