diff --git a/core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
index 0708e64..e795080 100644
--- a/core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/ConfigImportSubscriber.php
@@ -116,6 +116,8 @@ protected function validateModules(ConfigImporter $config_importer) {
       $config_importer->logError($this->t('Unable to install the %module module since it does not exist.', array('%module' => $module)));
     }
 
+    // Ensure that schema and version of the existing modules that produced the
+    // source configuration match the site.
     $existing_modules = array_keys(array_intersect_key($core_extension['module'], $config_importer->getStorageComparer()->getTargetStorage()->read('core.extension')['module']));
     foreach ($existing_modules as $module) {
       if ($core_extension['versions'][$module]['current'] !== $module_data[$module]->info['version']) {
@@ -202,6 +204,8 @@ protected function validateThemes(ConfigImporter $config_importer) {
       }
     }
 
+    // Ensure that version of the existing themes that produced the source
+    // configuration match the site.
     $existing_themes = array_keys(array_intersect_key($core_extension['theme'], $config_importer->getStorageComparer()->getTargetStorage()->read('core.extension')['theme']));
     foreach ($existing_themes as $theme) {
       if ($core_extension['versions'][$theme]['current'] !== $theme_data[$theme]->info['version']) {
diff --git a/core/modules/system/src/Tests/Extension/ThemeInstallerTest.php b/core/modules/system/src/Tests/Extension/ThemeInstallerTest.php
index 6fe81f7..b6b994c 100644
--- a/core/modules/system/src/Tests/Extension/ThemeInstallerTest.php
+++ b/core/modules/system/src/Tests/Extension/ThemeInstallerTest.php
@@ -269,6 +269,7 @@ function testUninstall() {
 
     $this->themeInstaller()->install(array($name));
     $this->assertTrue($this->config("$name.settings")->get());
+    $this->assertNotNull($this->config('core.extension')->get('versions.test_basetheme'), 'The "test_basetheme" version information is present after install.');
 
     $this->themeInstaller()->uninstall(array($name));
 
@@ -276,6 +277,7 @@ function testUninstall() {
     $this->assertFalse(array_keys(system_list('theme')));
 
     $this->assertFalse($this->config("$name.settings")->get());
+    $this->assertNull($this->config('core.extension')->get('versions.test_basetheme'), 'The "test_basetheme" version information is not present after uninstall.');
 
     // Ensure that the uninstalled theme can be installed again.
     $this->themeInstaller()->install(array($name));
diff --git a/core/modules/system/src/Tests/Module/UninstallTest.php b/core/modules/system/src/Tests/Module/UninstallTest.php
index 253ea18..de8cd2d 100644
--- a/core/modules/system/src/Tests/Module/UninstallTest.php
+++ b/core/modules/system/src/Tests/Module/UninstallTest.php
@@ -66,6 +66,10 @@ function testUninstallPage() {
     // Delete the node to allow node to be uninstalled.
     $node->delete();
 
+    // Ensure the module information is present in core.extension before
+    // uninstall.
+    $this->assertNotNull($this->config('core.extension')->get('versions.module_test'), 'The "module_test" version information is present.');
+
     // Uninstall module_test.
     $edit = array();
     $edit['uninstall[module_test]'] = TRUE;
@@ -76,6 +80,10 @@ function testUninstallPage() {
     $this->drupalPostForm(NULL, NULL, t('Uninstall'));
     $this->assertText(t('The selected modules have been uninstalled.'), 'Modules status has been updated.');
 
+    // Ensure the module information has been removed from core.extension after
+    // uninstall.
+    $this->assertNull($this->config('core.extension')->get('versions.module_test'), 'The "module_test" version information has been removed.');
+
     // Uninstall node testing that the configuration that will be deleted is
     // listed.
     $node_dependencies = \Drupal::service('config.manager')->findConfigEntityDependentsAsEntities('module', array('node'));