diff --git a/usr.sbin/mrouted/cfparse.y b/usr.sbin/mrouted/cfparse.y
index 2da4da36fcc6..b97bbed72265 100644
--- a/usr.sbin/mrouted/cfparse.y
+++ b/usr.sbin/mrouted/cfparse.y
@@ -347,7 +347,8 @@ interface	: ADDR		{ $$ = $1; }
 addrname	: ADDR		{ $$ = $1; }
 	| STRING		{ struct hostent *hp;
 
-				  if ((hp = gethostbyname($1)) == NULL)
+				  if ((hp = gethostbyname($1)) == NULL ||
+					hp->h_length != sizeof($$))
 				    fatal("No such host %s", $1);
 
 				  if (hp->h_addr_list[1])