diff --git a/CHANGES.rst b/CHANGES.rst
index 754b839b..bcd7ae56 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -3,6 +3,11 @@ All notable changes to this project will be documented in this file.
 The format is based on `Keep a Changelog <https://keepachangelog.com/en/1.0.0/>`_,
 and this project adheres to `Semantic Versioning <https://semver.org/spec/v2.0.0.html>`_.
 
+Fixed
+*****
+
+- Avoid crashing when LDAP groups references unexisting users.
+
 [0.0.35] - 2023-11-25
 =====================
 
diff --git a/canaille/backends/ldap/utils.py b/canaille/backends/ldap/utils.py
index bd0c2549..50eca69c 100644
--- a/canaille/backends/ldap/utils.py
+++ b/canaille/backends/ldap/utils.py
@@ -75,7 +75,7 @@ def python_to_ldap(value, syntax, encode=True):
         value = "TRUE" if value else "FALSE"
 
     if syntax == Syntax.DISTINGUISHED_NAME:
-        value = value.id
+        value = value.id if value else None
 
     if not value:
         return None