diff --git a/modules/simpletest/simpletest.test b/modules/simpletest/simpletest.test
index e5b6042..c8e9465 100644
--- a/modules/simpletest/simpletest.test
+++ b/modules/simpletest/simpletest.test
@@ -151,6 +151,16 @@ class SimpleTestFunctionalTest extends DrupalWebTestCase {
       // Regression test for #290316.
       // Check that test_id is incrementing.
       $this->assertTrue($this->test_ids[0] != $this->test_ids[1], t('Test ID is incrementing.'));
+
+      // Confirm that there are no tables remaining from the child test run.
+      $tables = db_find_tables('simpletest%');
+      foreach ($tables as $table) {
+        // Tables that are left over from the child installation will have two
+        // simpletest prefixes.
+        if (preg_match('/simpletest\d+simpletest.*comment/', $table)) {
+          $this->fail('Table from child simpletest installation was not cleaned up.');
+        }
+      }
     }
   }
 
@@ -176,6 +186,11 @@ class SimpleTestFunctionalTest extends DrupalWebTestCase {
     array_key_exists(NULL, NULL);
 
     debug('Foo', 'Debug');
+
+    // Enable and disable a module to ensure that clean up of database tables
+    // runs correctly.
+    module_enable(array('comment'));
+    module_disable(array('comment'));
   }
 
   /**