diff --git a/metricflow-semantics/metricflow_semantics/specs/time_dimension_spec.py b/metricflow-semantics/metricflow_semantics/specs/time_dimension_spec.py
index 4bb62825d6..2f23e3aa2e 100644
--- a/metricflow-semantics/metricflow_semantics/specs/time_dimension_spec.py
+++ b/metricflow-semantics/metricflow_semantics/specs/time_dimension_spec.py
@@ -155,7 +155,7 @@ def with_grain(self, time_granularity: ExpandedTimeGranularity) -> TimeDimension
         )
 
     def with_grain_and_date_part(  # noqa: D102
-        self, time_granularity: TimeGranularity, date_part: Optional[DatePart]
+        self, time_granularity: ExpandedTimeGranularity, date_part: Optional[DatePart]
     ) -> TimeDimensionSpec:
         return TimeDimensionSpec(
             element_name=self.element_name,