diff -Nru /n/sources/plan9/sys/src/libip/eipfmt.c /sys/src/libip/eipfmt.c
--- /n/sources/plan9/sys/src/libip/eipfmt.c	Sat May 14 19:07:06 2005
+++ /sys/src/libip/eipfmt.c	Sun Nov  6 00:00:00 2016
@@ -61,14 +61,14 @@
 		n = 0;
 		for(i = 0; i < 16; i += 2){
 			if(i == eli){
-				n += sprint(buf+n, "::");
+				n += snprint(buf+n, sizeof buf-n, "::");
 				i += eln;
 				if(i >= 16)
 					break;
 			} else if(i != 0)
-				n += sprint(buf+n, ":");
+				n += snprint(buf+n, sizeof buf-n, ":");
 			s = (p[i]<<8) + p[i+1];
-			n += sprint(buf+n, "%ux", s);
+			n += snprint(buf+n, sizeof buf-n, "%ux", s);
 		}
 		return fmtstrcpy(f, buf);
 
diff -Nru /n/sources/plan9/sys/src/libip/myetheraddr.c /sys/src/libip/myetheraddr.c
--- /n/sources/plan9/sys/src/libip/myetheraddr.c	Tue May  8 04:19:22 2007
+++ /sys/src/libip/myetheraddr.c	Sun Nov  6 00:00:00 2016
@@ -9,9 +9,9 @@
 	char buf[256];
 
 	if(*dev == '/')
-		sprint(buf, "%s/addr", dev);
+		snprint(buf, sizeof buf, "%s/addr", dev);
 	else
-		sprint(buf, "/net/%s/addr", dev);
+		snprint(buf, sizeof buf, "/net/%s/addr", dev);
 
 	fd = open(buf, OREAD);
 	if(fd < 0)