diff --git a/pyproject.toml b/pyproject.toml
index 07633c5716..28adeff292 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,10 @@ dependencies = [
   "decorator<=4.4.2",
   "mpi4py>3; python_version >= '3.13'",
   "mpi4py; python_version < '3.13'",
-  "h5py",
+  # TODO: We are only using our fork here because the most recent PyPI release
+  # does not yet work with build isolation for Python 3.13. Once a version
+  # newer than 3.12.1 is released we can revert to simply using "h5py".
+  "h5py @ git+https://github.com/firedrakeproject/h5py.git",
   "petsc4py",
   "numpy",
   "packaging",