diff --git a/guides/source/testing.md b/guides/source/testing.md
index 3f53ccb242..4caf55ab12 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -658,8 +658,8 @@ end
 
 The driver name is a required argument for `driven_by`. The optional arguments
 that can be passed to `driven_by` are `:using` for the browser (this will only
-be used for non-headless drivers like Selenium), `:on` for the port Puma should
-use, and `:screen_size` to change the size of the screen for screenshots.
+be used for non-headless drivers like Selenium), and `:screen_size` to change
+the size of the screen for screenshots.
 
 ```ruby
 require "test_helper"