Index: head/sys/netinet/igmp.c
===================================================================
--- head/sys/netinet/igmp.c
+++ head/sys/netinet/igmp.c
@@ -543,10 +543,10 @@
 	m = m_get(M_WAITOK, MT_DATA);
 	p = mtod(m, struct ipoption *);
 	p->ipopt_dst.s_addr = INADDR_ANY;
-	p->ipopt_list[0] = IPOPT_RA;	/* Router Alert Option */
-	p->ipopt_list[1] = 0x04;	/* 4 bytes long */
-	p->ipopt_list[2] = IPOPT_EOL;	/* End of IP option list */
-	p->ipopt_list[3] = 0x00;	/* pad byte */
+	p->ipopt_list[0] = (char)IPOPT_RA;	/* Router Alert Option */
+	p->ipopt_list[1] = 0x04;		/* 4 bytes long */
+	p->ipopt_list[2] = IPOPT_EOL;		/* End of IP option list */
+	p->ipopt_list[3] = 0x00;		/* pad byte */
 	m->m_len = sizeof(p->ipopt_dst) + p->ipopt_list[1];
 
 	return (m);