diff --git a/pyproject.toml b/pyproject.toml
index 47881ba..cace22e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "ophyd-registry"
-version = "1.2.0"
+version = "1.2.1"
 authors = [
   { name="Mark Wolfman", email="wolfman@anl.gov" },
 ]
diff --git a/src/ophydregistry/registry.py b/src/ophydregistry/registry.py
index c25a3f9..1ba6bc3 100644
--- a/src/ophydregistry/registry.py
+++ b/src/ophydregistry/registry.py
@@ -3,11 +3,16 @@
 import warnings
 from collections import OrderedDict
 from itertools import chain
-from typing import List, Mapping, Optional, Set
+from typing import Hashable, List, Mapping, Optional, Tuple
 from weakref import WeakSet, WeakValueDictionary
 
 from ophyd import ophydobj
 
+try:
+    from pcdsdevices.signal import _AggregateSignalState
+except ImportError:
+    _AggregateSignalState = ophydobj.OphydObject
+
 # Sentinal value for default parameters
 UNSET = object()
 
@@ -115,7 +120,7 @@ class Registry:
     use_typhos: bool
     keep_references: bool
     _auto_register: bool
-    _valid_classes: Set[type] = {ophydobj.OphydObject}
+    _valid_classes: Tuple[type] = (ophydobj.OphydObject, _AggregateSignalState)
 
     # components: Sequence
     _objects_by_name: Mapping
@@ -195,11 +200,12 @@ def pop(self, key, default=UNSET) -> ophydobj.OphydObject:
         # Remove from the list by name
         try:
             del self._objects_by_name[obj.name]
-        except KeyError:
+        except (KeyError, AttributeError):
             pass
         # Remove from the list by label
-        for objects in self._objects_by_label.values():
-            objects.discard(obj)
+        if isinstance(obj, Hashable):
+            for objects in self._objects_by_label.values():
+                objects.discard(obj)
         # Remove children from the lists as well
         sub_signals = getattr(obj, "_signals", {})
         for cpt_name, cpt in sub_signals.items():
@@ -346,9 +352,8 @@ def _is_resolved(self, obj):
         ``_valid_classes`` attribute with a new set.
 
         """
-        for cls in self._valid_classes:
-            if isinstance(obj, cls):
-                return True
+        if isinstance(obj, self._valid_classes):
+            return True
         return False
 
     def _findall_by_label(self, label, allow_none):
diff --git a/src/ophydregistry/tests/test_instrument_registry.py b/src/ophydregistry/tests/test_instrument_registry.py
index 0cac3fb..54add3b 100644
--- a/src/ophydregistry/tests/test_instrument_registry.py
+++ b/src/ophydregistry/tests/test_instrument_registry.py
@@ -13,7 +13,7 @@
 @pytest.fixture()
 def registry():
     reg = Registry(auto_register=False, use_typhos=False)
-    reg._valid_classes = {mock.MagicMock, *reg._valid_classes}
+    reg._valid_classes = (mock.MagicMock, *reg._valid_classes)
     try:
         yield reg
     finally: