diff -r ad317a5c7bfa -r 998fa71f4d36 src/pyams_content/shared/resource/schema.py
--- a/src/pyams_content/shared/resource/schema.py	Tue Jan 22 15:33:59 2019 +0100
+++ b/src/pyams_content/shared/resource/schema.py	Tue Jan 22 15:48:14 2019 +0100
@@ -38,7 +38,7 @@
     max_value = FieldProperty(IAgeRange['max_value'])
 
     def __bool__(self):
-        return self.min_value or self.max_value
+        return bool(self.min_value or self.max_value)
 
 
 class IAgeRangeField(IObject):