diff --git a/docs/conf.py b/docs/conf.py
index b0199d9..1962dea 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -41,6 +41,7 @@
 }
 
 # Other extension configs
+autodoc_use_legacy_class_based = True
 autodoc_default_options = {
     "members": True,
     "special-members": True,
diff --git a/invocations/autodoc.py b/invocations/autodoc.py
index fbff267..30e72e0 100644
--- a/invocations/autodoc.py
+++ b/invocations/autodoc.py
@@ -26,6 +26,9 @@
 
     - As noted above, this only works for modules that are importable, like any
       other Sphinx autodoc use case.
+    - For now, add ``autodoc_use_legacy_class_based = True`` to your
+      ``conf.py`` (see `sphinx-doc/sphinx#14089
+      <https://github.com/sphinx-doc/sphinx/issues/14089>`__).
     - Unless you want to opt-in which module members get documented, use
       ``:members:`` or add ``"members": True`` to your ``conf.py``'s
       ``autodoc_default_options``.
@@ -47,6 +50,7 @@
 
 # For sane mock patching. Meh.
 from sphinx.ext import autodoc
+from sphinx.util.inspect import stringify_signature
 
 
 class TaskDocumenter(
@@ -68,7 +72,7 @@ def format_args(self):
         # after which point "call tasks as raw functions" may be less common.
         # TODO: also, it may become moot-ish if we turn this all into emission
         # of custom domain objects and/or make the CLI arguments the focus
-        return autodoc.stringify_signature(inspect.signature(function))
+        return stringify_signature(inspect.signature(function))
 
     def document_members(self, all_members=False):
         # Neuter this so superclass bits don't introspect & spit out autodoc
diff --git a/tests/autodoc/_support/conf.py b/tests/autodoc/_support/conf.py
index a33252e..5e30750 100644
--- a/tests/autodoc/_support/conf.py
+++ b/tests/autodoc/_support/conf.py
@@ -7,4 +7,5 @@
 
 master_doc = "index"
 extensions = ["invocations.autodoc"]
+autodoc_use_legacy_class_based = True
 autodoc_default_options = dict(members=True)