diff --git a/client/sources/common/core.py b/client/sources/common/core.py
index a9371305..da287e70 100644
--- a/client/sources/common/core.py
+++ b/client/sources/common/core.py
@@ -6,7 +6,8 @@
 ###############
 
 class NoValue(object):
-    pass
+    def __bool__(self):
+        return False
 
 NoValue = NoValue()