diff --git a/synapse/util/ldap_auth_provider.py b/synapse/util/ldap_auth_provider.py
index f852e9b03..1b989248f 100644
--- a/synapse/util/ldap_auth_provider.py
+++ b/synapse/util/ldap_auth_provider.py
@@ -236,7 +236,8 @@ class LdapAuthProvider(object):
                 value=localpart,
                 base=self.ldap_base
             )
-            conn = ldap3.Connection(server, bind_dn, password)
+            conn = ldap3.Connection(server, bind_dn, password,
+                                    authentication=ldap3.AUTH_SIMPLE)
             logger.debug(
                 "Established LDAP connection in simple bind mode: %s",
                 conn