diff --git a/cps/admin.py b/cps/admin.py
index b709764b..3382e566 100755
--- a/cps/admin.py
+++ b/cps/admin.py
@@ -1631,7 +1631,10 @@ def import_ldap_users():
 
     imported = 0
     for username in new_users:
-        user = username.decode('utf-8')
+        if isinstance(username, bytes):
+            user = username.decode('utf-8')
+        else:
+            user = username
         if '=' in user:
             # if member object field is empty take user object as filter
             if config.config_ldap_member_user_object:
diff --git a/optional-requirements.txt b/optional-requirements.txt
index f4f0d169..7b27a63e 100644
--- a/optional-requirements.txt
+++ b/optional-requirements.txt
@@ -21,7 +21,7 @@ python-Levenshtein>=0.12.0,<0.26.0
 
 # ldap login
 python-ldap>=3.0.0,<3.5.0
-Flask-SimpleLDAP>=1.4.0,<1.5.0
+Flask-SimpleLDAP>=1.4.0,<2.1.0
 
 # oauth
 Flask-Dance>=2.0.0,<7.1.0