diff --git a/tests/isc/time_test.c b/tests/isc/time_test.c
index d3a7c016f4..26d2775725 100644
--- a/tests/isc/time_test.c
+++ b/tests/isc/time_test.c
@@ -280,7 +280,7 @@ ISC_RUN_TEST_IMPL(isc_time_formatISO8601TZms_test) {
 	assert_int_equal(buf[16], ':');
 	assert_int_equal(buf[19], '.');
 
-	size_t plus_minus[2] = { '+', '-' };
+	LargestIntegralType plus_minus[2] = { '+', '-' };
 	assert_in_set(buf[23], plus_minus, sizeof(plus_minus));
 	assert_int_equal(buf[26], ':');