--- a/mail/test/mozmill/composition/test-draft-identity.js
+++ b/mail/test/mozmill/composition/test-draft-identity.js
@@ -199,16 +199,17 @@ function test_draft_identity_selection()
   cwc.click_menus_in_sequence(cwc.e("msgIdentityPopup"),
                               [ { identitykey: gIdentities[0].key } ]);
 
   wait_for_notification_to_stop(cwc, "attachmentNotificationBox",
                                 "identityWarning");
   close_compose_window(cwc, false);
 */
 }
+test_draft_identity_selection.EXCLUDED_PLATFORMS = ["darwin"]; // See bug 1413851.
 
 function teardownModule(module) {
   for (let id = 1; id < gIdentities.length; id++) {
     gAccount.removeIdentity(MailServices.accounts.getIdentity(gIdentities[id].key));
   }
 
   // The last identity of an account can't be removed so clear all its prefs
   // which effectively destroys it.