time: don't segfault with no arguments

diff --git a/miscutils/time.c b/miscutils/time.c
index d8b8aa0..dbc92d1 100644
--- a/miscutils/time.c
+++ b/miscutils/time.c
@@ -402,6 +402,7 @@
 	const char *output_format = default_format;
 	int opt;
 
+	opt_complementary = "-1"; /* at least one arg */
 	/* "+": stop on first non-option */
 	opt = getopt32(argv, "+vp");
 	argv += optind;