diff --git a/modules/simpletest/tests/theme.test b/modules/simpletest/tests/theme.test
index 85f67b4..ba64400 100644
--- a/modules/simpletest/tests/theme.test
+++ b/modules/simpletest/tests/theme.test
@@ -111,6 +111,19 @@ class ThemeTestCase extends DrupalWebTestCase {
     $this->drupalGet('theme-test/suggestion');
     variable_set('preprocess_css', 0);
   }
+
+  /**
+   * Ensures the theme registry is rebuilt when modules are disabled/enabled.
+   */
+  function testRegistryRebuild() {
+    $this->assertIdentical(theme('theme_test_foo', array('foo' => 'a')), 'a', 'The theme registry contains theme_test_foo.');
+
+    module_disable(array('theme_test'), FALSE);
+    $this->assertIdentical(theme('theme_test_foo', array('foo' => 'b')), '', 'The theme registry does not contain theme_test_foo, because the module is disabled.');
+
+    module_enable(array('theme_test'), FALSE);
+    $this->assertIdentical(theme('theme_test_foo', array('foo' => 'c')), 'c', 'The theme registry contains theme_test_foo again after re-enabling the module.');
+  }
 }
 
 /**
diff --git a/modules/simpletest/tests/theme_test.module b/modules/simpletest/tests/theme_test.module
index cce7b80..a9bd2ad 100644
--- a/modules/simpletest/tests/theme_test.module
+++ b/modules/simpletest/tests/theme_test.module
@@ -14,6 +14,9 @@ function theme_test_theme($existing, $type, $theme, $path) {
   $items['theme_test_template_test_2'] = array(
     'template' => 'theme_test.template_test',
   );
+  $items['theme_test_foo'] = array(
+    'variables' => array('foo' => NULL),
+  );
   return $items;
 }
 
@@ -120,3 +123,10 @@ function _theme_test_alter() {
 function _theme_test_suggestion() {
   return theme(array('theme_test__suggestion', 'theme_test'), array());
 }
+
+/**
+ * Theme function for testing theme('theme_test_foo').
+ */
+function theme_theme_test_foo($variables) {
+  return $variables['foo'];
+}