diff --git a/attributs.py b/attributs.py
index c85d651..59302b6 100644
--- a/attributs.py
+++ b/attributs.py
@@ -200,7 +200,7 @@ class intAttr(Attr):
 
 class boolAttr(Attr):
     def parse_value(self, val, ldif):
-        if val.lower() == u'true':
+        if val.lower() in [u'true', u'ok']:
             self.value = True
         elif val.lower() == u'false':
             self.value = False