Index: stable/12/etc/mtree/BSD.tests.dist
===================================================================
--- stable/12/etc/mtree/BSD.tests.dist
+++ stable/12/etc/mtree/BSD.tests.dist
@@ -817,6 +817,8 @@
             ..
             link
             ..
+            mixer
+            ..
             mkdir
             ..
             mkfifo
Index: stable/12/usr.sbin/mixer/Makefile
===================================================================
--- stable/12/usr.sbin/mixer/Makefile
+++ stable/12/usr.sbin/mixer/Makefile
@@ -1,6 +1,11 @@
 # $FreeBSD$
 
+.include <src.opts.mk>
+
 PROG=	mixer
 MAN=	mixer.8
+
+HAS_TESTS=
+SUBDIR.${MK_TESTS}+= tests
 
 .include <bsd.prog.mk>
Index: stable/12/usr.sbin/mixer/mixer.c
===================================================================
--- stable/12/usr.sbin/mixer/mixer.c
+++ stable/12/usr.sbin/mixer/mixer.c
@@ -241,6 +241,11 @@
 		lrel = rrel = 0;
 		if (argc > 1) {
 			m = sscanf(argv[1], "%7[^:]:%7s", lstr, rstr);
+			if (m == EOF) {
+				warnx("invalid value: %s", argv[1]);
+				dusage = 1;
+				break;
+			}
 			if (m > 0) {
 				if (*lstr == '+' || *lstr == '-')
 					lrel = rrel = 1;
Index: stable/12/usr.sbin/mixer/tests/mixer_test.sh
===================================================================
--- stable/12/usr.sbin/mixer/tests/mixer_test.sh
+++ stable/12/usr.sbin/mixer/tests/mixer_test.sh
@@ -93,7 +93,7 @@
 	restore_mixer_vol
 }
 
-atf_test_case set_empty_value
+atf_test_case set_empty_value cleanup
 set_empty_value_head()
 {
 	atf_set	"descr" "Verify that mixer returns when the provided " \