diff --git a/src/js/fullscreen.js b/src/js/fullscreen.js
index c74b3406..6dc069b2 100644
--- a/src/js/fullscreen.js
+++ b/src/js/fullscreen.js
@@ -118,7 +118,7 @@ class Fullscreen {
 
         const element = !this.prefix ? document.fullscreenElement : document[`${this.prefix}${this.property}Element`];
 
-        return element === this.target;
+        return (element && element.shadowRoot) ? element === this.target.getRootNode().host : element === this.target;
     }
 
     // Get target element
diff --git a/src/js/utils/elements.js b/src/js/utils/elements.js
index b88aad0c..43f46416 100644
--- a/src/js/utils/elements.js
+++ b/src/js/utils/elements.js
@@ -221,7 +221,7 @@ export function hasClass(element, className) {
 
 // Element matches selector
 export function matches(element, selector) {
-    const prototype = { Element };
+    const prototype = Element.prototype;
 
     function match() {
         return Array.from(document.querySelectorAll(selector)).includes(this);