diff --git a/attributs.py b/attributs.py
index c4152a7..cf65fd7 100644
--- a/attributs.py
+++ b/attributs.py
@@ -271,6 +271,12 @@ class Attr(object):
         self.parent = Parent
         self.parse_value(val)
 
+    def __hash__(self):
+        if hasattr(self.value, "__hash__") and self.value.__hash__ is not None:
+            return self.value.__hash__()
+        else:
+            return str(self).__hash__()
+
     def __eq__(self, item):
         if isinstance(item, self.__class__):
             return str(self) == str(item)