diff --git a/README.md b/README.md
index afe124f3fb..39cf607617 100644
--- a/README.md
+++ b/README.md
@@ -204,7 +204,7 @@ The input variables, with their default values (some auto generated) are:
 - `stack_name`: (default: `"fastapi-project"`) The name of the stack used for Docker Compose labels and project name (no spaces, no periods) (in .env).
 - `secret_key`: (default: `"changethis"`) The secret key for the project, used for security, stored in .env, you can generate one with the method above.
 - `first_superuser`: (default: `"admin@example.com"`) The email of the first superuser (in .env).
-- `first_superuser_password`: (default: `"changethis"`) The password of the first superuser (in .env).
+- `first_superuser_password`: (default: `"changethis"`) The password of the first superuser (in .env). Must be 40 characters or less.
 - `smtp_host`: (default: "") The SMTP server host to send emails, you can set it later in .env.
 - `smtp_user`: (default: "") The SMTP server user to send emails, you can set it later in .env.
 - `smtp_password`: (default: "") The SMTP server password to send emails, you can set it later in .env.
diff --git a/copier.yml b/copier.yml
index f98e3fc861..5c7a4b66a2 100644
--- a/copier.yml
+++ b/copier.yml
@@ -23,7 +23,7 @@ first_superuser:
 
 first_superuser_password:
   type: str
-  help: The password of the first superuser (in .env)
+  help: The password of the first superuser (in .env), must be 40 characters or less
   default: changethis
 
 smtp_host:
diff --git a/deployment.md b/deployment.md
index eadf76ddae..4d4a0a39e6 100644
--- a/deployment.md
+++ b/deployment.md
@@ -132,7 +132,7 @@ You can set several variables, like:
 * `BACKEND_CORS_ORIGINS`: A list of allowed CORS origins separated by commas.
 * `SECRET_KEY`: The secret key for the FastAPI project, used to sign tokens.
 * `FIRST_SUPERUSER`: The email of the first superuser, this superuser will be the one that can create new users.
-* `FIRST_SUPERUSER_PASSWORD`: The password of the first superuser.
+* `FIRST_SUPERUSER_PASSWORD`: The password of the first superuser. Must be 40 characters or less.
 * `SMTP_HOST`: The SMTP server host to send emails, this would come from your email provider (E.g. Mailgun, Sparkpost, Sendgrid, etc).
 * `SMTP_USER`: The SMTP server user to send emails.
 * `SMTP_PASSWORD`: The SMTP server password to send emails.