diff --git a/core/modules/locale/src/Tests/LocaleConfigTranslationTest.php b/core/modules/locale/src/Tests/LocaleConfigTranslationTest.php
index 2370c1a..3f991aa 100644
--- a/core/modules/locale/src/Tests/LocaleConfigTranslationTest.php
+++ b/core/modules/locale/src/Tests/LocaleConfigTranslationTest.php
@@ -125,7 +125,7 @@ public function testConfigTranslation() {
     $this->assertFalse($string, 'Configuration strings have been created upon installation.');
 
     // Enable the image module.
-    $this->drupalPostForm('admin/modules', array('modules[Field Types][image][enable]' => "1"), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[field types][image][enable]' => "1"), t('Save configuration'));
     $this->rebuildContainer();
 
     $string = $this->storage->findString(array('source' => 'Medium (220×220)', 'context' => '', 'type' => 'configuration'));
diff --git a/core/modules/system/src/Form/ModulesListForm.php b/core/modules/system/src/Form/ModulesListForm.php
index ef853a1..5f89858 100644
--- a/core/modules/system/src/Form/ModulesListForm.php
+++ b/core/modules/system/src/Form/ModulesListForm.php
@@ -202,7 +202,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     $form['modules']['#tree'] = TRUE;
     foreach ($modules as $filename => $module) {
       if (empty($module->info['hidden'])) {
-        $package = ucwords($module->info['package']);
+        $package = strtolower($module->info['package']);
         $form['modules'][$package][$filename] = $this->buildRow($modules, $module, $distribution);
       }
     }
diff --git a/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php b/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php
index 3ef613c..876137c 100644
--- a/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php
+++ b/core/modules/system/src/Tests/Installer/InstallerTranslationTest.php
@@ -66,7 +66,7 @@ public function testInstaller() {
     $this->assertEqual($account->language()->getId(), 'de', 'New user is German.');
 
     // Ensure that we can enable basic_auth on a non-english site.
-    $this->drupalPostForm('admin/modules', array('modules[Web Services][basic_auth][enable]' => TRUE), t('Save configuration'));
+    $this->drupalPostForm('admin/modules', array('modules[web services][basic_auth][enable]' => TRUE), t('Save configuration'));
     $this->assertResponse(200);
 
     // Assert that the theme CSS was added to the page.
diff --git a/core/modules/system/src/Tests/Module/InstallUninstallTest.php b/core/modules/system/src/Tests/Module/InstallUninstallTest.php
index aa04033..1fdc2e4 100644
--- a/core/modules/system/src/Tests/Module/InstallUninstallTest.php
+++ b/core/modules/system/src/Tests/Module/InstallUninstallTest.php
@@ -136,7 +136,7 @@ public function testInstallUninstall() {
     //   any errors.
     $edit = array();
     foreach ($all_modules as $name => $module) {
-      $edit['modules[' . ucwords($module->info['package']) . '][' . $name . '][enable]'] = TRUE;
+      $edit['modules[' . strtolower($module->info['package']) . '][' . $name . '][enable]'] = TRUE;
     }
     $this->drupalPostForm('admin/modules', $edit, t('Save configuration'));
     $this->assertText(t('The configuration options have been saved.'), 'Modules status has been updated.');