diff --git a/usr.bin/uniq/tests/uniq_test.sh b/usr.bin/uniq/tests/uniq_test.sh
--- a/usr.bin/uniq/tests/uniq_test.sh
+++ b/usr.bin/uniq/tests/uniq_test.sh
@@ -74,6 +74,7 @@
 skip_fields_body() {
 	printf "1 a\n2 a\n3 b\n4 b\n5 a\n6 a\n" >input
 	printf "1 a\n3 b\n5 a\n" >expected
+	atf_check_uniq -1
 	atf_check_uniq -f 1
 	atf_check_uniq --skip-fields 1
 }
@@ -85,6 +86,7 @@
 skip_fields_tab_body() {
 	printf "1\ta\n2\ta\n3\tb\n4\tb\n5\ta\n6\ta\n" >input
 	printf "1\ta\n3\tb\n5\ta\n" >expected
+	atf_check_uniq -1
 	atf_check_uniq -f 1
 	atf_check_uniq --skip-fields 1
 }
@@ -107,6 +109,7 @@
 skip_chars_body() {
 	printf "1 a\n2 a\n3 b\n4 b\n5 a\n6 a\n" >input
 	printf "1 a\n3 b\n5 a\n" >expected
+	atf_check_uniq +2
 	atf_check_uniq -s 2
 	atf_check_uniq --skip-chars 2
 }
diff --git a/usr.bin/uniq/uniq.c b/usr.bin/uniq/uniq.c
--- a/usr.bin/uniq/uniq.c
+++ b/usr.bin/uniq/uniq.c
@@ -338,29 +338,25 @@
 static void
 obsolete(char *argv[])
 {
-	int len;
-	char *ap, *p, *start;
+	char *ap, *p;
 
 	while ((ap = *++argv)) {
 		/* Return if "--" or not an option of any form. */
 		if (ap[0] != '-') {
 			if (ap[0] != '+')
 				return;
-		} else if (ap[1] == '-')
+		} else if (ap[1] == '-') {
 			return;
+		}
 		if (!isdigit((unsigned char)ap[1]))
 			continue;
 		/*
 		 * Digit signifies an old-style option.  Malloc space for dash,
 		 * new option and argument.
 		 */
-		len = strlen(ap);
-		if ((start = p = malloc(len + 3)) == NULL)
+		if (asprintf(&p, "-%c%s", ap[0] == '+' ? 's' : 'f', ap + 1) < 0)
 			err(1, "malloc");
-		*p++ = '-';
-		*p++ = ap[0] == '+' ? 's' : 'f';
-		(void)strcpy(p, ap + 1);
-		*argv = start;
+		*argv = p;
 	}
 }