diff --git a/js/reveal.js b/js/reveal.js
index 4e4bf24..e093cb8 100644
--- a/js/reveal.js
+++ b/js/reveal.js
@@ -3122,6 +3122,9 @@
 				// Iframes
 				else if( backgroundIframe ) {
 					var iframe = document.createElement( 'iframe' );
+					iframe.setAttribute( 'allowfullscreen', '' );
+					iframe.setAttribute( 'mozallowfullscreen', '' );
+					iframe.setAttribute( 'webkitallowfullscreen', '' );
 
 					// Only load autoplaying content when the slide is shown to
 					// avoid having it play in the background