diff --git a/src/js/plugin/handler/keyboard.js b/src/js/plugin/handler/keyboard.js
index 2b38844..5c4db17 100644
--- a/src/js/plugin/handler/keyboard.js
+++ b/src/js/plugin/handler/keyboard.js
@@ -40,7 +40,7 @@ function bindKeyboardHandler(element, i) {
   }
 
   i.event.bind(i.ownerDocument, 'keydown', function (e) {
-    if (e.isDefaultPrevented && e.isDefaultPrevented() || e.defaultPrevented) {
+    if ((e.isDefaultPrevented && e.isDefaultPrevented()) || e.defaultPrevented) {
       return;
     }