diff --git a/doc/interop.rst b/doc/interop.rst
index a812d59f..557c71c1 100644
--- a/doc/interop.rst
+++ b/doc/interop.rst
@@ -52,7 +52,7 @@ straightforward. Some language is different:
   created by calling the function :func:`~firedrake.functionspace.FunctionSpace`
   and referred to as a "function space"
 * In a mesh, any vertices, faces, cells, etc. are :mod:`firedrake`
-  "entities" (see `the PETSc documentation on dmplex <https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DMPLEX/index.html>`__
+  "entities" (see `the PETSc documentation on DMPLEX <https://petsc.org/release/manualpages/DMPlex/>`__
   for more info on how topological mesh information is stored
   in :mod:`firedrake`).
 
diff --git a/meshmode/discretization/visualization.py b/meshmode/discretization/visualization.py
index 4a8c8d15..da56c679 100644
--- a/meshmode/discretization/visualization.py
+++ b/meshmode/discretization/visualization.py
@@ -932,7 +932,7 @@ def write_vtkhdf_file(self,
         # {{{ write
 
         # https://gitlab.kitware.com/vtk/vtk/-/merge_requests/7552/diffs?commit_id=ff63361e1e625bf5f8ff82a4063a9bc5b9f35818#92f6af7573e5302296e4d465fea1d411d4a2611d
-        # https://vtk.org/doc/nightly/html/VTKHDFFileFormat.html
+        # https://docs.vtk.org/en/latest/design_documents/VTKFileFormats.html#vtkhdf-file-format
 
         def create_dataset(grp, name, data, *, shape, offset):
             if data.ndim == 2 and data.shape[1] < 3: