diff --git a/lib/towerops_web/controllers/api/v1/gaiia_webhook_controller.ex b/lib/towerops_web/controllers/api/v1/gaiia_webhook_controller.ex
index 083b600f..1c90cd7c 100644
--- a/lib/towerops_web/controllers/api/v1/gaiia_webhook_controller.ex
+++ b/lib/towerops_web/controllers/api/v1/gaiia_webhook_controller.ex
@@ -149,7 +149,9 @@ defmodule ToweropsWeb.Api.V1.GaiiaWebhookController do
   defp check_timestamp(timestamp_str) do
     case Integer.parse(timestamp_str) do
       {ts, ""} ->
-        age = abs(System.system_time(:second) - ts)
+        # Gaiia sends timestamps in milliseconds — normalize to seconds
+        ts_seconds = if ts > 9_999_999_999, do: div(ts, 1000), else: ts
+        age = abs(System.system_time(:second) - ts_seconds)
         if age <= @max_age_seconds, do: :ok, else: {:error, :expired}
 
       _ ->