diff --git a/libraries/config/ConfigFile.class.php b/libraries/config/ConfigFile.class.php
index 41ffe4b07..7a15a89c2 100644
--- a/libraries/config/ConfigFile.class.php
+++ b/libraries/config/ConfigFile.class.php
@@ -174,6 +174,8 @@ class ConfigFile
     /**
      * Sets config value
      *
+     * @uses $GLOBALS['cfg']
+     * @uses PMA_array_read()
      * @uses PMA_array_remove()
      * @uses PMA_array_write()
      * @param string $path
@@ -190,13 +192,17 @@ class ConfigFile
             return;
         }
         // remove if the path isn't protected and it's empty or has a default value
-        $default_value = $this->getDefault($canonical_path);
-        if (!isset($this->persistKeys[$canonical_path])
-                && (($value === $default_value) || (empty($value) && empty($default_value)))) {
-            PMA_array_remove($path, $_SESSION[$this->id]);
-        } else {
-            PMA_array_write($path, $_SESSION[$this->id], $value);
+        if (!isset($this->persistKeys[$canonical_path])) {
+            $default_value = $this->getDefault($canonical_path);
+            // check $GLOBALS['cfg'] to allow overwriting options set in config.inc.php with default value
+            $current_global = PMA_array_read($canonical_path, $GLOBALS['cfg']);
+            if (($value === $default_value && (defined('PMA_SETUP') || $current_global === $default_value))
+                    || (empty($value) && empty($default_value) && (defined('PMA_SETUP') || empty($current_global)))) {
+                PMA_array_remove($path, $_SESSION[$this->id]);
+                return;
+            }
         }
+        PMA_array_write($path, $_SESSION[$this->id], $value);
     }
 
     /**
diff --git a/libraries/config/FormDisplay.class.php b/libraries/config/FormDisplay.class.php
index 5a08f5e87..fb0705227 100755
--- a/libraries/config/FormDisplay.class.php
+++ b/libraries/config/FormDisplay.class.php
@@ -498,7 +498,7 @@ class FormDisplay
 
         $values = array();
         $to_save = array();
-        $is_setup_script = defined('PMA_SETUP') && PMA_SETUP;
+        $is_setup_script = defined('PMA_SETUP');
         if ($is_setup_script) {
             $this->_loadUserprefsInfo();
         }
@@ -706,7 +706,7 @@ class FormDisplay
         if ($this->userprefs_keys === null) {
             $this->userprefs_keys = array_flip(PMA_read_userprefs_fieldnames());
             // read real config for user preferences display
-            $userprefs_disallow = defined('PMA_SETUP') && PMA_SETUP
+            $userprefs_disallow = defined('PMA_SETUP')
                 ? ConfigFile::getInstance()->get('UserprefsDisallow', array())
                 : $GLOBALS['cfg']['UserprefsDisallow'];
             $this->userprefs_disallow = array_flip($userprefs_disallow);
@@ -767,7 +767,7 @@ class FormDisplay
                 }
             }
         }
-        if (!defined('PMA_SETUP') || !PMA_SETUP) {
+        if (!defined('PMA_SETUP')) {
             if (($system_path == 'MaxDbList' || $system_path == 'MaxTableList'
                     || $system_path == 'QueryHistoryMax')) {
                 $opts['comment'] = sprintf(__('maximum %s'), $GLOBALS['cfg'][$system_path]);
diff --git a/libraries/config/FormDisplay.tpl.php b/libraries/config/FormDisplay.tpl.php
index 40c59d1c4..866720815 100644
--- a/libraries/config/FormDisplay.tpl.php
+++ b/libraries/config/FormDisplay.tpl.php
@@ -132,7 +132,7 @@ function display_input($path, $name, $description = '', $type, $value, $value_is
     global $_FormDisplayGroup;
     static $base_dir, $img_path;
 
-    $is_setup_script = defined('PMA_SETUP') && PMA_SETUP;
+    $is_setup_script = defined('PMA_SETUP');
     if ($base_dir === null) {
         $base_dir = $is_setup_script ? '../' : '';
         $img_path = $is_setup_script
@@ -298,7 +298,7 @@ function display_group_header($header_text)
         return;
     }
     $colspan = 2;
-    if (defined('PMA_SETUP') && PMA_SETUP) {
+    if (defined('PMA_SETUP')) {
         $colspan++;
     }
 ?>
@@ -328,7 +328,7 @@ function display_group_footer()
 function display_fieldset_bottom()
 {
     $colspan = 2;
-    if (defined('PMA_SETUP') && PMA_SETUP) {
+    if (defined('PMA_SETUP')) {
         $colspan++;
     }
 ?>
diff --git a/libraries/config/validate.lib.php b/libraries/config/validate.lib.php
index 7c35fffa7..59df2b8f4 100755
--- a/libraries/config/validate.lib.php
+++ b/libraries/config/validate.lib.php
@@ -29,7 +29,7 @@ function PMA_config_get_validators()
     if ($validators === null) {
         $cf = ConfigFile::getInstance();
         $validators = $cf->getDbEntry('_validators', array());
-        if (!defined('PMA_SETUP') || !PMA_SETUP) {
+        if (!defined('PMA_SETUP')) {
             $uvs = $cf->getDbEntry('_userValidators', array());
             foreach ($uvs as $field => $uv_list) {
                 $uv_list = (array)$uv_list;