diff --git a/js/navigation.js b/js/navigation.js
index a485fd1057..5f5edaa5db 100644
--- a/js/navigation.js
+++ b/js/navigation.js
@@ -72,7 +72,7 @@
 	/**
 	 * Sets or removes .focus class on an element.
 	 */
-	function toggleFocus() {
+	function toggleFocus(event) {
 		if ( event.type === 'focus' || event.type === 'blur' ) {
 			let self = this;
 			// Move up through the ancestors of the current link until we hit .nav-menu.