diff --git a/doc/040_backup.rst b/doc/040_backup.rst
index 70a5b0441..0a1d6b17e 100644
--- a/doc/040_backup.rst
+++ b/doc/040_backup.rst
@@ -378,6 +378,7 @@ environment variables. The following list of environment variables:
     RESTIC_REPOSITORY                   Location of repository (replaces -r)
     RESTIC_PASSWORD_FILE                Location of password file (replaces --password-file)
     RESTIC_PASSWORD                     The actual password for the repository
+    RESTIC_PASSWORD_COMMAND             Command printing the password for the repository to stdout
 
     AWS_ACCESS_KEY_ID                   Amazon S3 access key ID
     AWS_SECRET_ACCESS_KEY               Amazon S3 secret access key