diff --git a/src/helm/env.d/staging/values.desk.yaml.gotmpl b/src/helm/env.d/staging/values.desk.yaml.gotmpl
index abe2cc6..6a0d8da 100644
--- a/src/helm/env.d/staging/values.desk.yaml.gotmpl
+++ b/src/helm/env.d/staging/values.desk.yaml.gotmpl
@@ -71,7 +71,7 @@ backend:
     OIDC_RP_SCOPES: "openid email siret"
     OIDC_REDIRECT_ALLOWED_HOSTS: https://desk-staging.beta.numerique.gouv.fr
     OIDC_AUTH_REQUEST_EXTRA_PARAMS: "{'acr_values': 'eidas1'}"
-    ORGANIZATION_REGISTRATION_ID_VALIDATORS: '[{"NAME": "django.core.validators.RegexValidator", "OPTIONS": {"regex": "[a-z][0-9]{14}"}}]'
+    ORGANIZATION_REGISTRATION_ID_VALIDATORS: '[{"NAME": "django.core.validators.RegexValidator", "OPTIONS": {"regex": "^[0-9]{14}$"}}]'
     LOGIN_REDIRECT_URL: https://desk-staging.beta.numerique.gouv.fr
     LOGIN_REDIRECT_URL_FAILURE: https://desk-staging.beta.numerique.gouv.fr
     LOGOUT_REDIRECT_URL: https://desk-staging.beta.numerique.gouv.fr