diff --git a/datafusion/functions-aggregate/src/average.rs b/datafusion/functions-aggregate/src/average.rs
index 06c76946343d..ddd544a42a9c 100644
--- a/datafusion/functions-aggregate/src/average.rs
+++ b/datafusion/functions-aggregate/src/average.rs
@@ -970,6 +970,7 @@ where
     }
 
     fn size(&self) -> usize {
-        self.counts.capacity() * size_of::<u64>() + self.sums.capacity() * size_of::<T>()
+        self.counts.capacity() * size_of::<u64>()
+            + self.sums.capacity() * size_of::<T::Native>()
     }
 }
diff --git a/datafusion/functions-aggregate/src/median.rs b/datafusion/functions-aggregate/src/median.rs
index 4a0da10f5184..96410d652b35 100644
--- a/datafusion/functions-aggregate/src/median.rs
+++ b/datafusion/functions-aggregate/src/median.rs
@@ -543,10 +543,10 @@ impl<T: ArrowNumericType + Send> GroupsAccumulator for MedianGroupsAccumulator<T
     fn size(&self) -> usize {
         self.group_values
             .iter()
-            .map(|values| values.capacity() * size_of::<T>())
+            .map(|values| values.capacity() * size_of::<T::Native>())
             .sum::<usize>()
-            // account for size of self.grou_values too
-            + self.group_values.capacity() * size_of::<Vec<T>>()
+            // account for size of self.group_values too
+            + self.group_values.capacity() * size_of::<Vec<T::Native>>()
     }
 }