diff --git a/hwe/compare/fixtures/monthly_create_admin_npc.json b/hwe/compare/fixtures/monthly_create_admin_npc.json
new file mode 100644
index 00000000..74ca86de
--- /dev/null
+++ b/hwe/compare/fixtures/monthly_create_admin_npc.json
@@ -0,0 +1,9 @@
+{
+  "action": "CreateAdminNPC",
+  "environment": {
+    "year": 193,
+    "month": 12,
+    "startyear": 190
+  },
+  "observe": {}
+}
diff --git a/hwe/compare/monthly_event_trace.php b/hwe/compare/monthly_event_trace.php
index 69412e70..7ed323bb 100644
--- a/hwe/compare/monthly_event_trace.php
+++ b/hwe/compare/monthly_event_trace.php
@@ -184,6 +184,7 @@ function comparisonMonthlyEventTraceMain(): void
             'UpdateNationLevel',
             'ProcessSemiAnnual',
             'ProcessWarIncome',
+            'CreateAdminNPC',
         ];
         if (!in_array($actionName, $supportedActions, true)) {
             throw new \InvalidArgumentException('unsupported monthly action');