diff --git a/share/mk/Makefile b/share/mk/Makefile
index 549f5ea1f3b..d854cca705b 100644
--- a/share/mk/Makefile
+++ b/share/mk/Makefile
@@ -45,6 +45,7 @@ FILESDIR=	${BINDIR}/mk
 
 .if ${MK_TESTS} != "no"
 FILES+=	atf.test.mk
+FILES+=	plain.test.mk
 .endif
 
 .include <bsd.prog.mk>