diff --git a/source/Ox/js/String.js b/source/Ox/js/String.js
index 1454c5f7..3f89e93d 100644
--- a/source/Ox/js/String.js
+++ b/source/Ox/js/String.js
@@ -362,6 +362,8 @@ Ox.parseUserAgent = function(userAgent) {
                 '10.9': '10.9 (Mavericks)',
                 '10.10': '10.10 (Yosemite)',
                 '10.11': '10.11 (El Capitan)',
+                '10.12': '10.12 (Sierra)',
+                '10.13': '10.13 (High Sierra)',
                 'CrOS': 'Chrome OS',
                 'NT 4.0': 'NT 4.0 (Windows NT)',
                 'NT 4.1': 'NT 4.1 (Windows 98)',