diff --git a/lib/util/regress/atofoo/atofoo_test.c b/lib/util/regress/atofoo/atofoo_test.c
index 78b48758a..9b50b1e26 100644
--- a/lib/util/regress/atofoo/atofoo_test.c
+++ b/lib/util/regress/atofoo/atofoo_test.c
@@ -82,7 +82,7 @@ static struct strtoid_data {
     { "0,1", 0, ",", "," },
     { "10", 10, NULL, NULL },
     { "-2", -2, NULL, NULL },
-#if (id_t)-2 == 4294967294U
+#if SIZEOF_ID_T != SIZEOF_LONG_LONG
     { "-2", 4294967294U, NULL, NULL },
 #endif
     { "4294967294", 4294967294U, NULL, NULL },