diff --git a/docs/api/app.md b/docs/api/app.md
index a79b84a285a3..4ca67225b3f3 100644
--- a/docs/api/app.md
+++ b/docs/api/app.md
@@ -285,7 +285,7 @@ correctly.
 
 ### app.dock.bounce([type])
 
-* `type` String - Can be `critical` or `informational`. The default is
+* `type` String (optional) - Can be `critical` or `informational`. The default is
  `informational`
 
 When `critical` is passed, the dock icon will bounce until either the