diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index 45a5af05..7a92c1a0 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -27,7 +27,8 @@ jobs:
       #          install poetry
       #----------------------------------------------
       - name: Install Poetry
-        run: pipx install poetry
+        # Pin to 1.3.2 to workaround https://github.com/python-poetry/poetry/issues/7611
+        run: pipx install poetry==1.3.2
         
       #----------------------------------------------
       #       check-out repo and set-up python
diff --git a/linkml_runtime/utils/schemaview.py b/linkml_runtime/utils/schemaview.py
index 495b36a4..d65af31c 100644
--- a/linkml_runtime/utils/schemaview.py
+++ b/linkml_runtime/utils/schemaview.py
@@ -1453,21 +1453,20 @@ def get_slots_by_enum(self, enum_name: ENUM_NAME = None) -> List[SlotDefinition]
                         enum_slots.append(slot_definition)
         return enum_slots
 
-    def get_classes_modifying_slot(self, slot_name: SLOT_NAME = None) -> List[ClassDefinition]:
+    def get_classes_modifying_slot(self, slot: SlotDefinition) -> List[ClassDefinition]:
         """Get all ClassDefinitions that modify a given slot.
 
         :param slot_name: slot in consideration
         :return: list of ClassDefinitions modifying the slot of interest
         """
-        # slot_classes = [c for c in self.all_classes().values() if c.slot_usage == slot_name]
-        # slot_classes = [c for c in self.all_classes().values()]
-        slot_classes = []
+        modifying_classes = []
         for class_definition in self.all_classes().values():
             if class_definition.slot_usage:
                 for slot_definition in class_definition.slot_usage.values():
-                    if slot_definition.name == slot_name:
-                        slot_classes.append(class_definition)
-        return slot_classes
+                    if slot_definition.name == slot.name:
+                        modifying_classes.append(class_definition.name)
+
+        return modifying_classes
 
     def is_slot_percent_encoded(self, slot: SlotDefinitionName) -> bool:
         """
diff --git a/tests/test_issues/test_linkml_issue_1126.py b/tests/test_issues/test_linkml_issue_1126.py
index bb1cfb5c..fd69c1dd 100644
--- a/tests/test_issues/test_linkml_issue_1126.py
+++ b/tests/test_issues/test_linkml_issue_1126.py
@@ -2,7 +2,7 @@
 import unittest
 from unittest import TestCase
 from linkml_runtime.utils.schemaview import SchemaView
-from linkml_runtime.linkml_model import ClassDefinition
+from linkml_runtime.linkml_model import ClassDefinitionName
 
 from tests.test_issues.environment import env
 
@@ -16,13 +16,13 @@ class Issue998TestCase(TestCase):
 
     def test_issue_1126_slot_classes(self):
         view = SchemaView(env.input_path('linkml_issue_1126.yaml'))
-        slot_classes = view.get_classes_modifying_slot("type")
+        slot_definition = view.get_slot("type")
+        slot_classes = view.get_classes_modifying_slot(slot_definition)
         assert len(slot_classes) == 2
         for element in slot_classes:
-            assert type(element) is ClassDefinition
-        assert slot_classes[0].name == "Programmer"
-        assert slot_classes[1].name == "Administrator"
-
+            assert type(element) is ClassDefinitionName
+        assert slot_classes[0] == ClassDefinitionName("Programmer")
+        assert slot_classes[1] == ClassDefinitionName("Administrator")
 
 if __name__ == "__main__":
     unittest.main()