diff --git a/tests/sys/geom/class/nop/Makefile b/tests/sys/geom/class/nop/Makefile
index 54b41584d44..a3347e0cdb6 100644
--- a/tests/sys/geom/class/nop/Makefile
+++ b/tests/sys/geom/class/nop/Makefile
@@ -5,4 +5,8 @@ TESTSDIR=	${TESTSBASE}/sys/geom/class/${.CURDIR:T}
 
 ATF_TESTS_SH+=	nop_test
 
+# Some tests make use of the "disks" property and kyua may schedule
+# them to run at the time time, which the tests do not expect.
+TEST_METADATA.nop_test+= is_exclusive="true"
+
 .include <bsd.test.mk>