diff --git a/README.md b/README.md
index f76c63b..64807ee 100644
--- a/README.md
+++ b/README.md
@@ -33,9 +33,11 @@ Then just run jest and it will test errors PRs!
 ```
 
 ```sh
-jest file.js
+jest --testLocationInResults file.js
 ```
 
+(The `--testLocationInResults` flag is needed to get the in-file checks/annotations, otherwise only the summary comment is shown.)
+
 ## Using your own GitHub App
 
 You might not want to use our github app for the formatter.