diff -u b/core/modules/system/src/Tests/Form/ElementTest.php b/core/modules/system/src/Tests/Form/ElementTest.php
--- b/core/modules/system/src/Tests/Form/ElementTest.php
+++ b/core/modules/system/src/Tests/Form/ElementTest.php
@@ -106,6 +106,9 @@
     // A default value of FALSE indicates that nothing is set.
     $elements = $this->xpath('//input[@name="radios-boolean-false" and @checked]');
     $this->assertEqual(count($elements), 0);
+    $elements = $this->xpath('//input[@name="radios-boolean-any" and @checked]');
+    $this->assertEqual(count($elements), 1);
+    $this->assertIdentical((string) $elements[0]['value'], 'All');
   }
 
   /**
diff -u b/core/modules/system/tests/modules/form_test/src/Form/FormTestRadiosCheckedForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestRadiosCheckedForm.php
--- b/core/modules/system/tests/modules/form_test/src/Form/FormTestRadiosCheckedForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestRadiosCheckedForm.php
@@ -66,6 +66,16 @@
       ],
       '#default_value' => FALSE,
     ];
+    $form['radios-boolean-any'] = [
+      '#type' => 'radios',
+      '#title' => 'Radios',
+      '#options' => [
+        'All' => '- Any -',
+        1 => 'True',
+        0 => 'False',
+      ],
+      '#default_value' => 'All',
+    ];
 
     $form['submit'] = ['#type' => 'submit', '#value' => 'Submit'];