diff --git a/scripts/generate_psa_constants.py b/scripts/generate_psa_constants.py
index c441b4e..175cd9f 100755
--- a/scripts/generate_psa_constants.py
+++ b/scripts/generate_psa_constants.py
@@ -1,9 +1,14 @@
 #!/usr/bin/env python3
 
-"""Generate programs/psa/psa_constant_names_generated.c
+"""Generate psa_constant_names_generated.c
 which is included by programs/psa/psa_constant_names.c.
 The code generated by this module is only meant to be used in the context
 of that program.
+
+An argument passed to this script will modify the output directory where the
+file is written:
+* by default (no arguments passed): writes to programs/psa/
+* OUTPUT_FILE_DIR passed: writes to OUTPUT_FILE_DIR/
 """
 
 import os