diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index cfa01da9aab..67832d3814f 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -6821,14 +6821,20 @@ function normalize_component($component) {
 
 /**
  * List all core subsystems, this is especially useful for get_string()
- * and output renderers. The relative location is not always included.
+ * and output renderers.
+ *
+ * The location is dirroot relative path, NULL means there is no special
+ * directory for this subsystem.
+ *
+ * Unfortunately no module may be named like any core subsystem because
+ * we are still lazy to use proper "mod_" prefix in get_string() and elsewhere.
  *
  * @return array of strings - name=>location
  */
 function get_core_subsystems() {
     global $CFG;
 
-    static $info     = null;
+    static $info = null;
 
     if (!$info) {
         $info = array(
diff --git a/lib/outputfactories.php b/lib/outputfactories.php
index aebe7a28ca7..0707a7aef70 100644
--- a/lib/outputfactories.php
+++ b/lib/outputfactories.php
@@ -106,9 +106,6 @@ abstract class renderer_factory_base implements renderer_factory {
     /** @var theme_config the theme we belong to. */
     protected $theme;
 
-    /** @var hardcoded list of core subtypes and their locations, add more if ßneeded */
-    protected $core_subtypes = array('webservice' => 'webservice');
-
     /**
      * Constructor.
      * @param theme_config $theme the theme we belong to.
@@ -176,10 +173,11 @@ abstract class renderer_factory_base implements renderer_factory {
             }
 
         } else if (!empty($subtype)) {
-            if (!isset($this->core_subtypes[$subtype])) {
+            $coresubsystems = get_core_subsystems();
+            if (!isset($coresubsystems[$subtype])) {
                 throw new coding_exception('Invalid core subtype "' . $subtype . '" in renderer request');
             }
-            $rendererfile = $CFG->dirroot . '/' . $this->core_subtypes[$subtype] . '/renderer.php';
+            $rendererfile = $CFG->dirroot . '/' . $coresubsystems[$subtype] . '/renderer.php';
             if (file_exists($rendererfile)) {
                 include_once($rendererfile);
             }