diff -Nru /n/sources/plan9/sys/src/libhtml/lex.c /sys/src/libhtml/lex.c
--- /n/sources/plan9/sys/src/libhtml/lex.c	Mon Aug  6 00:37:30 2007
+++ /sys/src/libhtml/lex.c	Sun Nov  6 00:00:00 2016
@@ -1418,7 +1418,7 @@
 
 	t = va_arg(f->args, Token*);
 	if(t == nil)
-		sprint(buf, "<null>");
+		snprint(buf, sizeof buf, "<null>");
 	else {
 		i = 0;
 		if(dbglex > 1)