diff --git a/src/pygit2.c b/src/pygit2.c
index a4729df..20fd27a 100644
--- a/src/pygit2.c
+++ b/src/pygit2.c
@@ -281,7 +281,7 @@ moduleinit(PyObject* m)
     INIT_TYPE(TreeType, &ObjectType, NULL)
     INIT_TYPE(TreeEntryType, NULL, NULL)
     INIT_TYPE(TreeIterType, NULL, NULL)
-    INIT_TYPE(TreeBuilderType, NULL, PyType_GenericNew)
+    INIT_TYPE(TreeBuilderType, NULL, NULL)
     INIT_TYPE(BlobType, &ObjectType, NULL)
     INIT_TYPE(TagType, &ObjectType, NULL)
     ADD_TYPE(m, Object)