diff --git a/allensdk/brain_observatory/ecephys/stimulus_analysis/receptive_field_mapping.py b/allensdk/brain_observatory/ecephys/stimulus_analysis/receptive_field_mapping.py
index 74e75cabd..57ab351d6 100644
--- a/allensdk/brain_observatory/ecephys/stimulus_analysis/receptive_field_mapping.py
+++ b/allensdk/brain_observatory/ecephys/stimulus_analysis/receptive_field_mapping.py
@@ -284,8 +284,12 @@ def _response_by_stimulus_position(
         dataset[spike_count_key] = dataset.sum(dim=time_key)
         dataset = dataset.drop(time_key)
 
-        dataset[row_key] = presentations.loc[:, row_key]
-        dataset[column_key] = presentations.loc[:, column_key]
+        dataset = dataset.assign_coords(
+            {row_key: ("stimulus_presentation_id",
+                       presentations.loc[:, row_key].to_numpy())})
+        dataset = dataset.assign_coords(
+            {column_key: ("stimulus_presentation_id",
+                          presentations.loc[:, column_key].to_numpy())})
         dataset = dataset.to_dataframe()
 
         dataset = (