diff --git a/docs/source/conf.py b/docs/source/conf.py
index 5c806162..2b0a2e92 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -262,7 +262,7 @@ def _get_usd_ref_tooltip(app):
 
 
 @functools.cache
-def _get_url_for_target(app, target):
+def _get_url_for_usd_target(app, target):
     pxr_obj_namespace = target.removeprefix('pxr.').replace(".", "")
     pxr_obj_namespace = {
         "UsdInitialLoadSet": "UsdStage::InitialLoadSet",   # there's indirection in the python bindings
@@ -281,13 +281,9 @@ def _get_url_for_target(app, target):
 def _handle_missing_usd_reference(app, env, node, contnode):
     from docutils import nodes
 
-    target = node['reftarget']
-    if not target.startswith('pxr.'):
-        return None
-
-    reftitle, refuri = _get_url_for_target(app, target)
-    node = nodes.reference('', contnode.astext(), internal=False, refuri=refuri, reftitle=reftitle)
-    return node
+    if (target := node['reftarget']).startswith('pxr.'):
+        reftitle, refuri = _get_url_for_usd_target(app, target)
+        return nodes.reference('', contnode.astext(), internal=False, refuri=refuri, reftitle=reftitle)
 
 
 def _grill_process_signature(app, what, name, obj, options, signature, return_annotation):
diff --git a/grill/usd/__init__.py b/grill/usd/__init__.py
index 73814b88..fb56e69c 100644
--- a/grill/usd/__init__.py
+++ b/grill/usd/__init__.py
@@ -1,8 +1,7 @@
 """Helpers for USD workflows which do not know anything about the pipeline."""
+from __future__ import annotations
+
 import enum
-# https://docs.python.org/3/whatsnew/3.10.html#pep-604-new-type-union-operator
-# TODO: Remove when py-3.10+ is supported (for union types)
-import typing
 import inspect
 import logging
 import functools
@@ -58,7 +57,7 @@ def common_paths(paths: abc.Iterable[Sdf.Path]) -> list[Sdf.Path]:
     return unique
 
 
-def iprims(stage: Usd.Stage, root_paths: abc.Iterable[Sdf.Path] = tuple(), prune_predicate: abc.Callable[[Usd.Prim], bool] = None, traverse_predicate: typing.Union[Usd._Term, Usd._PrimFlagsConjunction] = Usd.PrimDefaultPredicate) -> abc.Iterator[Usd.Prim]:
+def iprims(stage: Usd.Stage, root_paths: abc.Iterable[Sdf.Path] = tuple(), prune_predicate: abc.Callable[[Usd.Prim], bool] = None, traverse_predicate: Usd._Term | Usd._PrimFlagsConjunction = Usd.PrimDefaultPredicate) -> abc.Iterator[Usd.Prim]:
     """Convenience function that creates an iterator useful for common :ref:`glossary:stage traversal`.
 
     Without keyword arguments, this is the same as calling :usdcpp:`UsdStage::Traverse`, so