diff -u b/core/modules/system/css/system.theme.css b/core/modules/system/css/system.theme.css
--- b/core/modules/system/css/system.theme.css
+++ b/core/modules/system/css/system.theme.css
@@ -85,6 +85,7 @@
 
 .form-required:after {
   color: #e00;
+  /* Use a Unicode symbol to prevent screen-readers from announcing the text. */
   content: " \204E ";
   line-height: 1;
   vertical-align: super;