Index: bin/pkill/tests/Makefile
===================================================================
--- bin/pkill/tests/Makefile
+++ bin/pkill/tests/Makefile
@@ -2,6 +2,11 @@
 
 .include <bsd.own.mk>
 
+# The test programs in this directory conflict with each other and also cause
+# spurious failures in other tests if run concurrently.  Run them exclusively
+# for the time being.
+TEST_METADATA+=			is_exclusive=true
+
 TAP_TESTS_SH=			pgrep-F_test
 TAP_TESTS_SH+=			pgrep-LF_test
 TAP_TESTS_SH+=			pgrep-P_test
Index: lib/libc/tests/sys/Makefile
===================================================================
--- lib/libc/tests/sys/Makefile
+++ lib/libc/tests/sys/Makefile
@@ -33,9 +33,13 @@
 NETBSD_ATF_TESTS_C+=		mmap_test
 NETBSD_ATF_TESTS_C+=		mprotect_test
 NETBSD_ATF_TESTS_C+=		msgctl_test
+TEST_METADATA.msgctl_test+=	is_exclusive=true
 NETBSD_ATF_TESTS_C+=		msgget_test
+TEST_METADATA.msgget_test+=	is_exclusive=true
 NETBSD_ATF_TESTS_C+=		msgrcv_test
+TEST_METADATA.msgrcv_test+=	is_exclusive=true
 NETBSD_ATF_TESTS_C+=		msgsnd_test
+TEST_METADATA.msgsnd_test+=	is_exclusive=true
 NETBSD_ATF_TESTS_C+=		msync_test
 NETBSD_ATF_TESTS_C+=		nanosleep_test
 NETBSD_ATF_TESTS_C+=		pipe_test