diff --git a/doc/conf.py b/doc/conf.py
index 7000e097594b331108cd3d278b877a0f051d3916..75f5beab79fd1130de91fc63a8598443f9a84192 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -29,6 +29,7 @@ intersphinx_mapping = {
     "jax": ("https://jax.readthedocs.io/en/latest/", None),
     "attrs": ("https://www.attrs.org/en/stable/", None),
     "mpi4py": ("https://mpi4py.readthedocs.io/en/latest", None),
+    "immutabledict": ("https://immutabledict.corenting.fr/", None),
 }
 
 # Some modules need to import things just so that sphinx can resolve symbols in
@@ -47,9 +48,4 @@ nitpick_ignore_regex = [
     ["py:class", r"numpy.(u?)int[\d]+"],
     ["py:class", r"numpy.bool_"],
     ["py:class", r"typing_extensions(.+)"],
-    # As of 2023-10-05, it doesn't look like there's sphinx documentation
-    # available.
-    ["py:class", r"immutabledict(.*)"],
-    # https://github.com/python-attrs/attrs/issues/1073
-    ["py:mod", "attrs"],
 ]