diff --git a/bitbake/lib/bb/COW.py b/bitbake/lib/bb/COW.py
index 76bc08a3ea..4af03c54ad 100644
--- a/bitbake/lib/bb/COW.py
+++ b/bitbake/lib/bb/COW.py
@@ -36,8 +36,9 @@ class COWDictMeta(COWMeta):
     __marker__ = tuple()
 
     def __str__(cls):
-        # FIXME: I have magic numbers!
-        return "<COWDict Level: %i Current Keys: %i>" % (cls.__count__, len(cls.__dict__) - 3)
+        ignored_keys = set(["__count__", "__doc__", "__module__", "__firstlineno__", "__static_attributes__"])
+        keys = set(cls.__dict__.keys()) - ignored_keys
+        return "<COWDict Level: %i Current Keys: %i>" % (cls.__count__, len(keys))
 
     __repr__ = __str__
 
@@ -161,8 +162,9 @@ class COWDictMeta(COWMeta):
 
 class COWSetMeta(COWDictMeta):
     def __str__(cls):
-        # FIXME: I have magic numbers!
-        return "<COWSet Level: %i Current Keys: %i>" % (cls.__count__, len(cls.__dict__) - 3)
+        ignored_keys = set(["__count__", "__doc__", "__module__", "__firstlineno__", "__static_attributes__"])
+        keys = set(cls.__dict__.keys()) - ignored_keys
+        return "<COWSet Level: %i Current Keys: %i>" % (cls.__count__, len(keys))
 
     __repr__ = __str__