diff --git a/docs/index.md b/docs/index.md
index b6a70eba7c..ebc7758922 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -936,6 +936,10 @@ Define a global variable name. For example, suppose your app deliberately expose
 
 By using this option in conjunction with `--check-leaks`, you can specify a whitelist of known global variables that you _expect_ to leak into global scope.
 
+### `--posix-exit-codes`
+
+Exits with standard POSIX exit codes instead of the number of faled tests.
+
 ### `--retries <n>`
 
 Retries failed tests `n` times.