diff --git a/src/pydantic2linkml/gen_linkml.py b/src/pydantic2linkml/gen_linkml.py
index 0ca4f2d3..ad331f2f 100644
--- a/src/pydantic2linkml/gen_linkml.py
+++ b/src/pydantic2linkml/gen_linkml.py
@@ -1189,7 +1189,7 @@ def _computed_field_schema(self, schema: core_schema.ComputedField) -> None:
         )
 
 
-def translate_defs(module_names) -> SchemaDefinition:
+def translate_defs(module_names: Iterable[str]) -> SchemaDefinition:
     """
     Translate Python objects, in the named modules and their submodules loaded to
         `sys.modules`, to LinkML