diff --git a/cli/src/pcluster/validators/directory_service_validators.py b/cli/src/pcluster/validators/directory_service_validators.py
index 2ee4962b53..b1f0ba03a0 100644
--- a/cli/src/pcluster/validators/directory_service_validators.py
+++ b/cli/src/pcluster/validators/directory_service_validators.py
@@ -60,7 +60,7 @@ class DomainNameValidator(Validator):
     """Domain name validator."""
 
     FQDN_PATTERN = "^([a-zA-Z0-9_-]+)(\\.[a-zA-Z0-9_-]+)*$"
-    LDAP_DN_PATTERN = "^((DC|dc)=[a-zA-Z0-9_-]+)(,(DC|dc)=[a-zA-Z0-9_-]+)*$"
+    LDAP_DN_PATTERN = "^((DC|dc|O|o)=[a-zA-Z0-9_-]+)(,(DC|dc)=[a-zA-Z0-9_-]+)*$"
 
     def _validate(self, domain_name):
         """Validate that domain address is a Fully Qualified Domain Name (FQDN) or a LDAP Distinguished Name (DN)."""
diff --git a/cli/tests/pcluster/validators/test_directory_service_validators.py b/cli/tests/pcluster/validators/test_directory_service_validators.py
index 232f68f324..6f1e2e2407 100644
--- a/cli/tests/pcluster/validators/test_directory_service_validators.py
+++ b/cli/tests/pcluster/validators/test_directory_service_validators.py
@@ -35,12 +35,15 @@
         ("DC=corp,DC=example,DC=com", None),
         ("dc=corp,dc=example,dc=com", None),
         ("dc=corp,DC=example,dc=com", None),
+        ("O=org,dc=corp,dc=example,dc=com", None),
+        ("o=org,dc=corp,dc=example,dc=com", None),
         ("", DOMAIN_NAME_ERROR_MESSAGE),
         ("   ", DOMAIN_NAME_ERROR_MESSAGE),
         ("corp.", DOMAIN_NAME_ERROR_MESSAGE),
         ("DC=corp,", DOMAIN_NAME_ERROR_MESSAGE),
         ("corp.examp/e.com", DOMAIN_NAME_ERROR_MESSAGE),
         ("DC=corp,DC=examp/e,DC=com", DOMAIN_NAME_ERROR_MESSAGE),
+        ("o=or/g,dc=corp,dc=example,dc=com", DOMAIN_NAME_ERROR_MESSAGE),
     ],
 )
 def test_domain_name(domain_name, expected_message):