diff --git a/closure/goog/useragent/platform.js b/closure/goog/useragent/platform.js
index 0f56670a85..67a048594f 100644
--- a/closure/goog/useragent/platform.js
+++ b/closure/goog/useragent/platform.js
@@ -33,7 +33,7 @@ goog.userAgent.platform.determineVersion_ = function() {
       return '0';
     }
   } else if (goog.userAgent.MAC) {
-    re = /10[_.][0-9_.]+/;
+    re = /1[0|1][_.][0-9_.]+/;
     var match = re.exec(goog.userAgent.getUserAgentString());
     // Note: some old versions of Camino do not report an OSX version.
     // Default to 10.
diff --git a/closure/goog/useragent/platform_test.js b/closure/goog/useragent/platform_test.js
index 1e138467e8..037d14d1b6 100644
--- a/closure/goog/useragent/platform_test.js
+++ b/closure/goog/useragent/platform_test.js
@@ -75,6 +75,10 @@ testSuite({
     const ff = 'Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US;' +
         'rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 GTB6';
 
+    const chrome_osx_11 = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 11_1_0)' +
+        'AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66' +
+        'Safari/537.36';
+
     mockAgent.setNavigator({platform: 'IntelMac'});
 
     mockAgent.setUserAgentString(chrome);
@@ -84,6 +88,10 @@ testSuite({
     mockAgent.setUserAgentString(ff);
     updateUserAgentUtils();
     assertEquals('10.5', platform.VERSION);
+
+    mockAgent.setUserAgentString(chrome_osx_11);
+    updateUserAgentUtils();
+    assertEquals('11.1.0', platform.VERSION);
   },
 
   testChromeOnAndroid() {