diff --git a/bibtexparser/middlewares/__init__.py b/bibtexparser/middlewares/__init__.py
index 2cccafe..243eff4 100644
--- a/bibtexparser/middlewares/__init__.py
+++ b/bibtexparser/middlewares/__init__.py
@@ -24,5 +24,6 @@
     SortFieldsAlphabeticallyMiddleware,
     SortFieldsCustomMiddleware,
 )
+from bibtexparser.middlewares.middleware import BlockMiddleware, LibraryMiddleware
 
 from .parsestack import default_parse_stack, default_unparse_stack