diff --git a/passerelle/apps/ldap/models.py b/passerelle/apps/ldap/models.py
index 82631703..28fef1d7 100644
--- a/passerelle/apps/ldap/models.py
+++ b/passerelle/apps/ldap/models.py
@@ -34,6 +34,8 @@ from passerelle.utils.templates import render_to_string
 
 from . import forms
 
+LDAP_HAS_OPT_X_TLS_REQUIRE_SAN = hasattr(ldap, 'OPT_X_TLS_REQUIRE_SAN')  # only in python-ldap >= 3.4.0
+
 SEARCH_OP_SUBSTRING = 'substring'
 SEARCH_OP_PREFIX = 'prefix'
 SEARCH_OP_APPROX = 'approx'
@@ -70,6 +72,9 @@ class Resource(BaseResource):
         verbose_name=_('TLS check hostname'),
         default=True,
         blank=True,
+        help_text=None
+        if LDAP_HAS_OPT_X_TLS_REQUIRE_SAN
+        else _('Warning: this option is actually not supported (python-ldap < 3.4)'),
     )
     ldap_tls_check_cert = models.BooleanField(
         verbose_name=_('TLS check certificate'),
@@ -123,10 +128,11 @@ class Resource(BaseResource):
         conn = ldap.initialize(self.ldap_url)
         conn.set_option(ldap.OPT_TIMEOUT, 5)
         conn.set_option(ldap.OPT_NETWORK_TIMEOUT, 5)
-        if self.ldap_tls_check_hostname:
-            conn.set_option(ldap.OPT_X_TLS_REQUIRE_SAN, ldap.OPT_X_TLS_DEMAND)
-        else:
-            conn.set_option(ldap.OPT_X_TLS_REQUIRE_SAN, ldap.OPT_X_TLS_NEVER)
+        if LDAP_HAS_OPT_X_TLS_REQUIRE_SAN:
+            if self.ldap_tls_check_hostname:
+                conn.set_option(ldap.OPT_X_TLS_REQUIRE_SAN, ldap.OPT_X_TLS_DEMAND)
+            else:
+                conn.set_option(ldap.OPT_X_TLS_REQUIRE_SAN, ldap.OPT_X_TLS_NEVER)
         if self.ldap_tls_check_cert:
             conn.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_DEMAND)
         else:
diff --git a/tests/ldap/test_manager.py b/tests/ldap/test_manager.py
index 7a8aa950..48dfc4ae 100644
--- a/tests/ldap/test_manager.py
+++ b/tests/ldap/test_manager.py
@@ -41,6 +41,7 @@ def app(app, admin_user):
 
 def test_add(app, db, cert_content, key_content, resource_class):
     response = app.get('/manage/ldap/add')
+    assert 'this option is actually not supported' in response.text
     response.form.set('slug', 'resource')
     response.form.set('title', 'resource')
     response.form.set('description', 'resource')
@@ -101,6 +102,11 @@ def test_missing_tls_cert(app, db, cert_content, key_content, resource_class):
     response = response.form.submit(status=200)
 
 
+def test_python_ldap_32(app, db):
+    response = app.get('/manage/ldap/add')
+    assert 'Warning: this option is actually not supported (python-ldap < 3.4)' in response.text
+
+
 EXPORT_JSON = {
     'resources': [
         {
diff --git a/tests/ldap/test_search_endpoint.py b/tests/ldap/test_search_endpoint.py
index 2f8dbd4c..36f22f31 100644
--- a/tests/ldap/test_search_endpoint.py
+++ b/tests/ldap/test_search_endpoint.py
@@ -68,14 +68,12 @@ def test_server_unavailaible(app, resource):
             'id_attribute': 'uid',
         },
     )
-    assert response.json == {
-        'data': [{'disabled': True, 'id': '', 'text': 'Directory server is unavailable'}],
-        'err': 1,
-        'err_class': 'directory-server-unavailable',
-        'err_desc': '{\'result\': -1, \'desc\': "Can\'t contact LDAP server", '
-        "'errno': 107, 'ctrls': [], 'info': 'Transport endpoint is not "
-        "connected'}",
-    }
+    assert response.json['err'] == 1
+    assert response.json['data'] == [{'disabled': True, 'id': '', 'text': 'Directory server is unavailable'}]
+    assert response.json['err_class'] == 'directory-server-unavailable'
+    assert "'info': 'Transport endpoint is not connected'" in response.json['err_desc']
+    assert "'errno': 107" in response.json['err_desc']
+    assert "'desc': \"Can't contact LDAP server\"" in response.json['err_desc']
 
 
 def test_q(app, resource, ldap_server):
diff --git a/tox.ini b/tox.ini
index 5f4645f8..dc77d43c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -47,6 +47,7 @@ deps =
   zeep<3.3
   codestyle: pre-commit
   ldaptools
+  python-ldap<=3.2  # align with Debian <= 11 (buster, bullseye)
 commands =
   ./get_wcs.sh
   py.test {posargs: --numprocesses {env:NUMPROCESSES:1} --dist loadfile {env:FAST:} {env:COVERAGE:} {env:JUNIT:} tests/}