diff --git a/kernel/time/time_test.c b/kernel/time/time_test.c
index 831e8e779ace..ca058c8af6ba 100644
--- a/kernel/time/time_test.c
+++ b/kernel/time/time_test.c
@@ -86,7 +86,7 @@ static void time64_to_tm_test_date_range(struct kunit *test)
 }
 
 static struct kunit_case time_test_cases[] = {
-	KUNIT_CASE(time64_to_tm_test_date_range),
+	KUNIT_CASE_SLOW(time64_to_tm_test_date_range),
 	{}
 };