Index: Objects/setobject.c
===================================================================
--- Objects/setobject.c	(revision 61667)
+++ Objects/setobject.c	(working copy)
@@ -984,9 +984,15 @@
 			return NULL;
 	}
 
+        if (type != &PySet_Type && type != &PyFrozenSet_Type) {
+            if (PyType_IsSubtype(type, &PySet_Type))
+                type = &PySet_Type;
+            else
+                type = &PyFrozenSet_Type;
+        }
+
 	/* create PySetObject structure */
-	if (numfree &&
-	    (type == &PySet_Type  ||  type == &PyFrozenSet_Type)) {
+	if (numfree) {
 		so = free_list[--numfree];
 		assert (so != NULL && PyAnySet_CheckExact(so));
 		Py_TYPE(so) = type;