diff --git a/install/lang/sv/langconfig.php b/install/lang/sv/langconfig.php
index 8065d5bdda1..47aa43d0c75 100644
--- a/install/lang/sv/langconfig.php
+++ b/install/lang/sv/langconfig.php
@@ -29,5 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
+// Warning: this parentlanguage value is not a valid language code!
+// $string['parentlanguage'] = 'Överliggande språk';
 $string['thisdirection'] = 'ltr';
 $string['thislanguage'] = 'Svenska';
diff --git a/install/lang/sv/moodle.php b/install/lang/sv/moodle.php
index 3c7e43187c9..c5e80d50831 100644
--- a/install/lang/sv/moodle.php
+++ b/install/lang/sv/moodle.php
@@ -32,5 +32,5 @@ defined('MOODLE_INTERNAL') || die();
 $string['language'] = 'Språk';
 $string['moodlelogo'] = 'Moodie-logotyp';
 $string['next'] = 'Nästa';
-$string['previous'] = 'Tidigare';
+$string['previous'] = 'Föregående';
 $string['reload'] = 'Uppdatera';
diff --git a/install/lang/yo/langconfig.php b/install/lang/yo/langconfig.php
new file mode 100644
index 00000000000..1da38a643ec
--- /dev/null
+++ b/install/lang/yo/langconfig.php
@@ -0,0 +1,32 @@
+<?php
+// This file is part of Moodle - https://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <https://www.gnu.org/licenses/>.
+
+/**
+ * Automatically generated strings for Moodle installer
+ *
+ * Do not edit this file manually! It contains just a subset of strings
+ * needed during the very first steps of installation. This file was
+ * generated automatically by export-installer.php (which is part of AMOS
+ * {@link http://docs.moodle.org/dev/Languages/AMOS}) using the
+ * list of strings defined in /install/stringnames.txt.
+ *
+ * @package   installer
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+$string['thislanguage'] = 'Yorùbá';