diff --git a/zebra/rt_socket.c b/zebra/rt_socket.c
index 67d2953..f9f194e 100644
--- a/zebra/rt_socket.c
+++ b/zebra/rt_socket.c
@@ -146,7 +146,7 @@
 	  else
 	    {
 	      masklen2ip (p->prefixlen, &sin_mask.sin_addr);
-	      sin_mask.sin_family = AF_UNSPEC;
+	      sin_mask.sin_family = AF_INET;
 #ifdef HAVE_SIN_LEN
 	      sin_mask.sin_len = sin_masklen (sin_mask.sin_addr);
 #endif /* HAVE_SIN_LEN */