diff --git a/parsedmarc/resources/maps/README.md b/parsedmarc/resources/maps/README.md
index faaaceb..24845cd 100644
--- a/parsedmarc/resources/maps/README.md
+++ b/parsedmarc/resources/maps/README.md
@@ -72,11 +72,11 @@ A list of reverse DNS base domains that could not be identified as belonging to
 
 ## base_reverse_dns.csv
 
-A CSV with the fields `base_reverse_dns` and optionally `count`. This CSV can be generated byy exporting the base DNS data from the Kibana on Splunk dashboards provided by parsedmarc. This file is not tracked by Git.
+A CSV with the fields `source_name` and optionally `message_countcount`. This CSV can be generated byy exporting the base DNS data from the Kibana on Splunk dashboards provided by parsedmarc. This file is not tracked by Git.
 
 ## unknown_base_reverse_dns.csv
 
-A CSV file with the fields `base_reverse_dns` and `count`. This file is not tracked by Git.
+A CSV file with the fields `source_name` and `message_count`. This file is not tracked by Git.
 
 ## find_unknown_base_reverse_dns.py
 
diff --git a/parsedmarc/resources/maps/find_unknown_base_reverse_dns.py b/parsedmarc/resources/maps/find_unknown_base_reverse_dns.py
index a5568ca..83c85fd 100755
--- a/parsedmarc/resources/maps/find_unknown_base_reverse_dns.py
+++ b/parsedmarc/resources/maps/find_unknown_base_reverse_dns.py
@@ -11,7 +11,7 @@ def _main():
     known_unknown_list_file_path = "known_unknown_base_reverse_dns.txt"
     output_csv_file_path = "unknown_base_reverse_dns.csv"
 
-    csv_headers = ["base_reverse_dns", "count"]
+    csv_headers = ["source_name", "message_count"]
 
     output_rows = []
 
@@ -54,7 +54,7 @@ def _main():
     logger.info(f"Checking domains against {base_reverse_dns_map_file_path}")
     with open(input_csv_file_path) as f:
         for row in csv.DictReader(f):
-            domain = row["base_reverse_dns"].lower().strip()
+            domain = row["source_name"].lower().strip()
             if domain not in known_domains or known_unknown_domains:
                 logger.info(f"New unknown domain found: {domain}")
                 output_rows.append(row)