diff --git a/test/modules/acos.js b/test/modules/acos.js
index 49bdc6d..5fffc01 100644
--- a/test/modules/acos.js
+++ b/test/modules/acos.js
@@ -69,6 +69,7 @@ T('acos', function () {
   t('-0.19508761025300975791021816036', 27, 1, '1.76714310275532020878366926');
   t('0.0623252416', 19, 0, '1.508430664767542249');
   t('0.9999999297625', 14, 4, '0.00037479994883195');
+  t('0.99999999467518', 14, 4, '0.00010319709302810');
 
   /*
   t('0.95', 6, 5, '0.31756');