diff --git a/src/pg/sql/41_observatory_augmentation.sql b/src/pg/sql/41_observatory_augmentation.sql
index 98a8ec7..a5b3fd6 100644
--- a/src/pg/sql/41_observatory_augmentation.sql
+++ b/src/pg/sql/41_observatory_augmentation.sql
@@ -518,8 +518,25 @@ DECLARE
   q_sum text;
   q text;
   i NUMERIC;
+  data_geoid_colname text;
+  geom_geoid_colname text;
 BEGIN
 
+  -- TODO we're assuming our geom_table has only one geom_ref column
+  --      we *really* should pass in both geom_table_name and boundary_id
+  -- TODO tablename should not be passed here (use boundary_id)
+  EXECUTE
+    format('SELECT ct.colname
+              FROM observatory.obs_column_to_column c2c,
+                   observatory.obs_column_table ct,
+                   observatory.obs_table t
+             WHERE c2c.reltype = ''geom_ref''
+               AND ct.column_id = c2c.source_id
+               AND ct.table_id = t.id
+               AND t.tablename = %L'
+   , geom_table_name)
+  INTO geom_geoid_colname;
+
   q_select := 'SELECT geoid, ';
   q_sum    := 'SELECT Array[';
 
@@ -555,8 +572,8 @@ BEGIN
 
   q := q || q_select || format('FROM observatory.%I ', ((data_table_info)[1]->>'tablename'));
 
-  q := q || ' ) ' || q_sum || ' ]::numeric[] FROM _overlaps, values
-  WHERE values.geoid = _overlaps.geoid';
+  q := format(q || ' ) ' || q_sum || ' ]::numeric[] FROM _overlaps, values
+  WHERE values.%I = _overlaps.%I', geom_geoid_colname, geom_geoid_colname);
 
   EXECUTE
     q