diff -u b/core/modules/system/image.gd.inc b/core/modules/system/image.gd.inc
--- b/core/modules/system/image.gd.inc
+++ b/core/modules/system/image.gd.inc
@@ -43,9 +43,11 @@
  * @see system_image_toolkit_settings_submit
  */
 function image_gd_settings_submit($form, &$form_state) {
-  config('system.image.gd')
-    ->set('jpeg_quality', $form_state['values']['image_jpeg_quality'])
-    ->save();
+  if (isset($form_state['values']['image_jpeg_quality'])) {
+    config('system.image.gd')
+      ->set('jpeg_quality', $form_state['values']['image_jpeg_quality'])
+      ->save();
+  }
 }
 
 /**
diff -u b/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
--- b/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -1862,25 +1862,11 @@
   $current_toolkit = image_get_toolkit();
 
-  if (count($toolkits_available) == 0) {
-    $config->set('toolkit', '')->save();
-    $form['image_toolkit_help'] = array(
-      '#markup' => t("No image toolkits were detected. Drupal includes support for <a href='!gd-link'>PHP's built-in image processing functions</a> but they were not detected on this system. You should consult your system administrator to have them enabled, or try using a third party toolkit.", array('gd-link' => url('http://php.net/gd'))),
-    );
-    return $form;
-  }
-
   $form['image_toolkit'] = array(
     '#type' => 'radios',
     '#title' => t('Select an image processing toolkit'),
     '#default_value' => $config->get('toolkit'),
     '#options' => $toolkits_available,
-    '#access' => count($toolkits_available) > 1,
   );
 
-  if (count($toolkits_available) == 1) {
-    // Set the image toolkit to the one only available.
-    $config->set('toolkit', key($toolkits_available))->save();
-  }
-
   // Get the toolkit's settings form.
   $function = 'image_' . $current_toolkit . '_settings';
@@ -1901,7 +1887,7 @@
 
   // Call the form submit handler for the current toolkit. Calling
   // image_get_toolkit() does the necessary includes.
-  $function = 'image_' . image_get_toolkit() . '_settings_submit';
+  $function = 'image_' . $form_state['values']['image_toolkit'] . '_settings_submit';
   if (function_exists($function)) {
     $function($form, $form_state);
   }