diff --git a/earthdiagnostics/ocean/sivolume.py b/earthdiagnostics/ocean/sivolume.py
index 40b6227d841658292f03f996756e7c65e2fcef64..39c4a38caa13fb12aaddf02c86dc35085b92b48e 100644
--- a/earthdiagnostics/ocean/sivolume.py
+++ b/earthdiagnostics/ocean/sivolume.py
@@ -98,7 +98,7 @@ class Sivolume(Diagnostic):
         area = e1t * e2t
 
         for basin in basins:
-            masks[basin] = Utils.get_mask(basin) * area.data
+            masks[basin] = Utils.get_mask(basin) * area.core_data()
 
         job_list = list()
         for (
@@ -175,19 +175,19 @@ class Sivolume(Diagnostic):
             condition = data.coord("latitude").points > 0
         else:
             condition = data.coord("latitude").points < 0
-        weights = (
-            iris.util.broadcast_to_shape(
-                condition, data.shape, data.coord_dims("latitude")
-            )
-            * mask
-        )
+        new_mask = condition * mask
+        if new_mask.max() == 0:
+            return None
+        data = data * new_mask
         return data.collapsed(
-            ("latitude", "longitude"), iris.analysis.SUM, weights=weights
+            ("latitude", "longitude"), iris.analysis.SUM
         )
 
     def save(self, var, results):
         cubes = iris.cube.CubeList()
         for basin, result in six.iteritems(results):
+            if result is None:
+                continue
             result.var_name = var
             result.units = "m^3"
             result.add_aux_coord(