diff --git a/tests/sys/kern/Makefile b/tests/sys/kern/Makefile
index e674329f77b..0a422f42cdd 100644
--- a/tests/sys/kern/Makefile
+++ b/tests/sys/kern/Makefile
@@ -10,7 +10,10 @@ TESTSRC=	${SRCTOP}/contrib/netbsd-tests/kernel
 TESTSDIR=	${TESTSBASE}/sys/kern
 
 ATF_TESTS_C+=	basic_signal
-#ATF_TESTS_C+=	kcov
+.if ${MACHINE_ARCH} != "i386" && ${MACHINE_ARCH} != "powerpc"
+# No support for atomic_load_64 on i386 or (32-bit) powerpc
+ATF_TESTS_C+=	kcov
+.endif
 ATF_TESTS_C+=	kern_copyin
 ATF_TESTS_C+=	kern_descrip_test
 ATF_TESTS_C+=	fdgrowtable_test
diff --git a/tests/sys/kern/kcov.c b/tests/sys/kern/kcov.c
index 0a59ddbeff7..a8a43faf2d1 100644
--- a/tests/sys/kern/kcov.c
+++ b/tests/sys/kern/kcov.c
@@ -340,7 +340,7 @@ ATF_TC_BODY(kcov_thread_cmp, tc)
 }
 
 struct multi_thread_data {
-	char *buf;
+	uint64_t *buf;
 	int fd;
 	u_int mode;
 	int thread;