diff --git a/pyproject.toml b/pyproject.toml
index 9d82c52..68f370d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,6 +38,7 @@ mkdocstrings = { version = "*", optional = true, extras = ["python-legacy"] }
 mkdocs-awesome-pages-plugin = { version = "*", optional = true }
 mkdocs-jupyter = { version = "*", optional = true }
 notebook = { version = "*", optional = true }
+typing-extensions = "*"
 
 [tool.poetry.extras]
 test = ["pytest", "beautifulsoup4", "pre-commit"]