diff --git a/requirements.txt b/requirements.txt
index 72590eb..4c28074 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,6 @@
 numpy
 scipy
+typing_extensions
 
 # development
 pytest
diff --git a/setup.py b/setup.py
index 3e143de..c1e52d4 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
 
 setup(
     name="killeengeo",
-    version="0.0.4",
+    version="0.0.5",
     description="2D and 3D geometry in Python.",
     long_description=long_description,
     long_description_content_type="text/markdown",
@@ -18,6 +18,7 @@
     install_requires=[
         "numpy",
         "scipy",
+        "typing_extensions",
     ],
     packages=find_packages(where="src"),
     package_dir={"": "src"},