diff -Nru /n/sources/plan9/sys/src/cmd/ndb/cs.c /sys/src/cmd/ndb/cs.c
--- /n/sources/plan9/sys/src/cmd/ndb/cs.c	Fri Mar 30 20:41:12 2012
+++ /sys/src/cmd/ndb/cs.c	Sun Nov  6 00:00:00 2016
@@ -970,7 +970,7 @@
 {
 	if(myipaddr(ipa, mntpt) != 0)
 		ipmove(ipa, IPnoaddr);
-	sprint(ipaddr, "%I", ipa);
+	snprint(ipaddr, sizeof ipaddr, "%I", ipa);
 	if (debug)
 		syslog(0, "dns", "ipaddr is %s\n", ipaddr);
 }
diff -Nru /n/sources/plan9/sys/src/cmd/ndb/dblookup.c /sys/src/cmd/ndb/dblookup.c
--- /n/sources/plan9/sys/src/cmd/ndb/dblookup.c	Tue May 17 16:32:17 2011
+++ /sys/src/cmd/ndb/dblookup.c	Sun Nov  6 00:00:00 2016
@@ -1064,7 +1064,7 @@
 			net[IPv4off+1] = atoi(f[2]);
 			net[IPv4off+2] = atoi(f[1]);
 			net[IPv4off+3] = atoi(f[0]);
-			sprint(ipa, "%I", net);
+			snprint(ipa, sizeof ipa, "%I", net);
 			t = ndbipinfo(db, "ip", ipa, attribs, 1);
 			if(t == nil)	/* could be a reverse with no forward */
 				continue;
diff -Nru /n/sources/plan9/sys/src/cmd/ndb/dnudpserver.c /sys/src/cmd/ndb/dnudpserver.c
--- /n/sources/plan9/sys/src/cmd/ndb/dnudpserver.c	Wed Feb 19 20:03:42 2014
+++ /sys/src/cmd/ndb/dnudpserver.c	Sun Nov  6 00:00:00 2016
@@ -281,7 +281,7 @@
 	static int whined;
 
 	/* get a udp port */
-	sprint(datafile, "%s/udp!*!dns", mntpt);
+	snprint(datafile, sizeof datafile, "%s/udp!*!dns", mntpt);
 	ctl = announce(datafile, dir);
 	if(ctl < 0){
 		if(!whined++)