diff --git a/README.md b/README.md
index 2d8cce7d007eafcd84682b3479737436d98d8c99..a9f56315f856e354c0711e677c33a962539a7d1c 100644
--- a/README.md
+++ b/README.md
@@ -9,4 +9,4 @@ Copy `config-sample.json` to `config.json` and update the values.
 
 ## Use
 
-Set up a cron entry to run the program periodically, or manually call it when your IP address changes. The program accepts no arguments, as `config.json` handles everything.
+Set up a cron entry to run the program periodically, or manually call it when your IP address changes. The program accepts a single argument, `-config`, pointing to a `config.json` file that handles everything. A sample `config.json` is provided in the form of `config-sample.json`.