diff --git a/src/core/constants.py b/src/core/constants.py
index 1e5ac7e8..db7240bf 100644
--- a/src/core/constants.py
+++ b/src/core/constants.py
@@ -376,7 +376,7 @@ class Const(object):
     def bool(cls, value):
         """@return (bool): bool value for associated constant"""
         assert isinstance(value, basestring)
-        return value.lower() in (cls.BOOL_TRUE, "1")
+        return value.lower() in (cls.BOOL_TRUE, "1", "yes")
 
     @classmethod
     def boolConst(cls, value):