diff --git a/README.md b/README.md
index 8c73e53..824b623 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ It permutes `argv` to handle multiple values for each option and to assign
 values to operands.
 
 `mdoc(7)` `SYNOPSIS` sections and plaintext usage messages can be generated as
-well (via `readoptPutUsage`).
+well (via `readopt_put_usage`).
 
 An example can be found in `test/test.c`.