diff --git a/yt/data_objects/octree_subset.py b/yt/data_objects/octree_subset.py
index 54ad9b7c273..6b580ab9666 100644
--- a/yt/data_objects/octree_subset.py
+++ b/yt/data_objects/octree_subset.py
@@ -507,6 +507,10 @@ def _fill_fields(self, fields):
         data_in = {}
         for f in fields:
             data_in[f] = self._base_grid[f]
+        for f in ['x', 'y', 'z', 'dx']:
+            if f in fields:
+                continue
+            data_in[f] = self._base_grid[f]
 
         data_out = self.oct_handler.get_hypercube(
             self._base_grid, data_in