diff --git a/core/modules/simpletest/src/AssertContentTrait.php b/core/modules/simpletest/src/AssertContentTrait.php
index 1969c6b..169624e 100644
--- a/core/modules/simpletest/src/AssertContentTrait.php
+++ b/core/modules/simpletest/src/AssertContentTrait.php
@@ -1160,7 +1160,7 @@ protected function assertNoFieldChecked($id, $message = '', $group = 'Browser')
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertOption($id, $option, $message = '', $group = 'Browser') {
-    $options = $this->xpath('//select[contains(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
+    $options = $this->xpath('//select[starts-with(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
     return $this->assertTrue(isset($options[0]), $message ? $message : SafeMarkup::format('Option @option for field @id exists.', array('@option' => $option, '@id' => $id)), $group);
   }
 
@@ -1210,8 +1210,8 @@ protected function assertOptionWithDrupalSelector($drupal_selector, $option, $me
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertNoOption($id, $option, $message = '', $group = 'Browser') {
-    $selects = $this->xpath('//select[contains(@id, :id)]', array(':id' => $id));
-    $options = $this->xpath('//select[contains(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
+    $selects = $this->xpath('//select[starts-with(@id, :id)]', array(':id' => $id));
+    $options = $this->xpath('//select[starts-with(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
     return $this->assertTrue(isset($selects[0]) && !isset($options[0]), $message ? $message : SafeMarkup::format('Option @option for field @id does not exist.', array('@option' => $option, '@id' => $id)), $group);
   }
 
@@ -1236,7 +1236,7 @@ protected function assertNoOption($id, $option, $message = '', $group = 'Browser
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertOptionSelected($id, $option, $message = '', $group = 'Browser') {
-    $elements = $this->xpath('//select[contains(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
+    $elements = $this->xpath('//select[starts-with(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
     return $this->assertTrue(isset($elements[0]) && !empty($elements[0]['selected']), $message ? $message : SafeMarkup::format('Option @option for field @id is selected.', array('@option' => $option, '@id' => $id)), $group);
   }
 
@@ -1259,8 +1259,6 @@ protected function assertOptionSelected($id, $option, $message = '', $group = 'B
    *
    * @return bool
    *   TRUE on pass, FALSE on fail.
-   *
-   * @todo $id is unusable. Replace with $name.
    */
   protected function assertOptionSelectedWithDrupalSelector($drupal_selector, $option, $message = '', $group = 'Browser') {
     $elements = $this->xpath('//select[@data-drupal-selector=:data_drupal_selector]//option[@value=:option]', array(':data_drupal_selector' => $drupal_selector, ':option' => $option));
@@ -1288,7 +1286,7 @@ protected function assertOptionSelectedWithDrupalSelector($drupal_selector, $opt
    *   TRUE on pass, FALSE on fail.
    */
   protected function assertNoOptionSelected($id, $option, $message = '', $group = 'Browser') {
-    $elements = $this->xpath('//select[contains(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
+    $elements = $this->xpath('//select[starts-with(@id, :id)]//option[@value=:option]', array(':id' => $id, ':option' => $option));
     return $this->assertTrue(isset($elements[0]) && empty($elements[0]['selected']), $message ? $message : SafeMarkup::format('Option @option for field @id is not selected.', array('@option' => $option, '@id' => $id)), $group);
   }