diff --git a/lib/mentat/reports/event.py b/lib/mentat/reports/event.py
index 0b33b40cb8f87a8699ea3811e39f745d4c78e483..179c30393ae932f1a16269b20b516965d25b9b80 100644
--- a/lib/mentat/reports/event.py
+++ b/lib/mentat/reports/event.py
@@ -549,9 +549,9 @@ class EventReporter(BaseReporter):
                     seen[filtered_groups] = []
                 if filtered_groups not in aggregated_result:
                     aggregated_result[filtered_groups] = {}
-                if src not in aggregated_result[filtered_groups]:
-                    aggregated_result[filtered_groups][src] = []
-                aggregated_result[filtered_groups][src].append(event)
+                if str(src) not in aggregated_result[filtered_groups]:
+                    aggregated_result[filtered_groups][str(src)] = []
+                aggregated_result[filtered_groups][str(src)].append(event)
                 if event['ID'] not in seen[filtered_groups]:
                     result[filtered_groups].append(event)
                     seen[filtered_groups].append(event['ID'])