diff --git a/src/ifcopenshell-python/pyproject.toml b/src/ifcopenshell-python/pyproject.toml
index 28595d7a0d..dc8db46e66 100644
--- a/src/ifcopenshell-python/pyproject.toml
+++ b/src/ifcopenshell-python/pyproject.toml
@@ -13,6 +13,8 @@ classifiers = [
     "Programming Language :: Python :: 3",
     "License :: OSI Approved :: GNU Lesser General Public License v3 or later (LGPLv3+)",
 ]
+[project.optional-dependencies]
+geometry = ["mathutils"]
 [project.urls]
 "Homepage" = "http://ifcopenshell.org"
 "Bug Tracker" = "https://github.com/ifcopenshell/ifcopenshell/issues"