diff --git a/lib/classes/filetypes.php b/lib/classes/filetypes.php
index cea82ed1973..f4d09c6bd15 100644
--- a/lib/classes/filetypes.php
+++ b/lib/classes/filetypes.php
@@ -313,6 +313,9 @@ abstract class core_filetypes {
             'xml' => array('type' => 'application/xml', 'icon' => 'markup'),
             'xsl' => array('type' => 'text/xml', 'icon' => 'markup'),
 
+            'yaml' => array('type' => 'application/yaml', 'icon' => 'markup'),
+            'yml' => array('type' => 'application/yaml', 'icon' => 'markup'),
+
             'zip' => array('type' => 'application/zip', 'icon' => 'archive', 'groups' => array('archive'), 'string' => 'archive')
         );
     }
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index e8bfaf584a3..0405aa1d0a6 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -3064,5 +3064,27 @@ privatefiles,moodle|/user/files.php';
         upgrade_main_savepoint(true, 2022112803.03);
     }
 
+    if ($oldversion < 2022112804.08) {
+        // Upgrade yaml mime type for existing yaml and yml files.
+        $filetypes = array(
+            '%.yaml' => 'application/yaml',
+            '%.yml' => 'application/yaml,'
+        );
+
+        $select = $DB->sql_like('filename', '?', false);
+        foreach ($filetypes as $extension => $mimetype) {
+            $DB->set_field_select(
+                'files',
+                'mimetype',
+                $mimetype,
+                $select,
+                array($extension)
+            );
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2022112804.08);
+    }
+
     return true;
 }