diff --git a/core/modules/simpletest/simpletest.install b/core/modules/simpletest/simpletest.install
index df19ccc..524ceff 100644
--- a/core/modules/simpletest/simpletest.install
+++ b/core/modules/simpletest/simpletest.install
@@ -190,8 +190,74 @@ function simpletest_update_8102() {
     'description' => 'The name of the class that created this message.',
   );
   $schema = Database::getConnection()->schema();
+  // Index 'reporter' uses 'test_class', so remove and recreate it.
+  $schema->dropIndex('simpletest', 'reporter');
   $schema->changeField('simpletest', 'test_class', 'test_class', $simpletest_test_class);
-
+  // Spec of the table once we've done the two previous operations. We need
+  // this to recreate the index.
+  $spec = array(
+    'description' => 'Stores simpletest messages',
+    'fields' => array(
+      'message_id'  => array(
+        'type' => 'serial',
+        'not null' => TRUE,
+        'description' => 'Primary Key: Unique simpletest message ID.',
+      ),
+      'test_id' => array(
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'Test ID, messages belonging to the same ID are reported together',
+      ),
+      'test_class' => array(
+        'type' => 'text',
+        'not null' => TRUE,
+        'description' => 'The name of the class that created this message.',
+      ),
+      'status' => array(
+        'type' => 'varchar',
+        'length' => 9,
+        'not null' => TRUE,
+        'default' => '',
+        'description' => 'Message status. Core understands pass, fail, exception.',
+      ),
+      'message' => array(
+        'type' => 'text',
+        'not null' => TRUE,
+        'description' => 'The message itself.',
+      ),
+      'message_group' => array(
+        'type' => 'varchar_ascii',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+        'description' => 'The message group this message belongs to. For example: warning, browser, user.',
+      ),
+      'function' => array(
+        'type' => 'varchar_ascii',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+        'description' => 'Name of the assertion function or method that created this message.',
+      ),
+      'line' => array(
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'description' => 'Line number on which the function is called.',
+      ),
+      'file' => array(
+        'type' => 'varchar',
+        'length' => 255,
+        'not null' => TRUE,
+        'default' => '',
+        'description' => 'Name of the file where the function is called.',
+      ),
+    ),
+    'primary key' => array('message_id'),
+  );
+  $schema->addIndex('simpletest', 'reporter', array(array('test_class', 255), 'message_id'), $spec);
+  
   $simpletest_function = array(
     'type' => 'text',
     'not null' => TRUE,