diff --git a/lib/medialib.php b/lib/medialib.php
index 0d0bd3579db..7b364166d95 100644
--- a/lib/medialib.php
+++ b/lib/medialib.php
@@ -494,7 +494,8 @@ class core_media_player_vimeo extends core_media_player_external {
         $output = <<<OET
 <span class="mediaplugin mediaplugin_vimeo">
 <iframe title="$info" src="https://player.vimeo.com/video/$videoid"
-  width="$width" height="$height" frameborder="0"></iframe>
+  width="$width" height="$height" frameborder="0"
+  webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>
 </span>
 OET;