diff --git a/keyboardjs/keyboardjs.d.ts b/keyboardjs/keyboardjs.d.ts
index e4247234ea..820101dd67 100644
--- a/keyboardjs/keyboardjs.d.ts
+++ b/keyboardjs/keyboardjs.d.ts
@@ -29,7 +29,7 @@ declare namespace keyboardjs {
         /**
 		 * Keyevent
 		 */
-        (e: KeyEvent): void;
+        (e?: KeyEvent): void;
     }
 
     // ---------- Key Binding ---------- //