diff --git a/README.md b/README.md
index c4301e9..98e859b 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 checkpw is a program that checks the validity of a users password on a Linux/PAM-based system.
 
+Returns 0 on success, 1 otherwise.
+
 # Installation:
 
 ```