diff --git a/lib/outputlib.php b/lib/outputlib.php
index dab6f7c7ed2..dc84f4ab21d 100644
--- a/lib/outputlib.php
+++ b/lib/outputlib.php
@@ -1593,7 +1593,7 @@ class theme_config {
 
         // Getting all the candidate functions.
         $candidates = array();
-        foreach ($this->parent_configs as $parent_config) {
+        foreach (array_reverse($this->parent_configs) as $parent_config) {
             if (!isset($parent_config->extrascsscallback)) {
                 continue;
             }
@@ -1626,7 +1626,7 @@ class theme_config {
 
         // Getting all the candidate functions.
         $candidates = array();
-        foreach ($this->parent_configs as $parent_config) {
+        foreach (array_reverse($this->parent_configs) as $parent_config) {
             if (!isset($parent_config->prescsscallback)) {
                 continue;
             }
diff --git a/theme/boost/lib.php b/theme/boost/lib.php
index 7e98100f6d8..6cc398d535e 100644
--- a/theme/boost/lib.php
+++ b/theme/boost/lib.php
@@ -135,7 +135,7 @@ function theme_boost_get_precompiled_css() {
  * Get SCSS to prepend.
  *
  * @param theme_config $theme The theme config object.
- * @return array
+ * @return string
  */
 function theme_boost_get_pre_scss($theme) {
     global $CFG;