diff --git a/sphinx_d2lang/__init__.py b/sphinx_d2lang/__init__.py
index a273d0b..0ef71de 100644
--- a/sphinx_d2lang/__init__.py
+++ b/sphinx_d2lang/__init__.py
@@ -1,3 +1,5 @@
+from sphinx.application import Sphinx
+
 from .d2lang import D2langDirective
 
 def setup(application: Sphinx) -> Dict[str, Any]: