diff --git a/python/CASE2GeoJSON.py b/python/CASE2GeoJSON.py
index d635b29..56654b7 100644
--- a/python/CASE2GeoJSON.py
+++ b/python/CASE2GeoJSON.py
@@ -6,6 +6,7 @@
 from geotypes import GeoRecord
 from geoutilities import records_to_geojson, remove_nulls
 from rdflib import Graph
+from rdflib.query import ResultRow
 
 # Parse the arguments from the CLI to get the input and output filenames
 if len(sys.argv) != 3:
@@ -64,6 +65,7 @@
 
 # Loop through the results and add them to the list of GeoRecords if the latitude and longitude are present
 for row in results:
+    assert isinstance(row, ResultRow)
     geo_record: GeoRecord = GeoRecord()
     geo_record.Latitude = row.lLatitude
     geo_record.Longitude = row.lLongitude