diff --git a/lib/microwaveprop_web/metrics_plug.ex b/lib/microwaveprop_web/metrics_plug.ex
index eaf8a654..440bdaf4 100644
--- a/lib/microwaveprop_web/metrics_plug.ex
+++ b/lib/microwaveprop_web/metrics_plug.ex
@@ -18,6 +18,12 @@ defmodule MicrowavepropWeb.MetricsPlug do
       :ok ->
         body = PromEx.get_metrics(Microwaveprop.PromEx)
 
+        # Defer the ETS cron flusher; otherwise it runs every
+        # `ets_flush_interval` (7.5s) concurrently with scrapes and its
+        # `Task.await` (hardcoded 10s) trips under contention, killing
+        # the GenServer. Upstream `PromEx.Plug` does the same.
+        PromEx.ETSCronFlusher.defer_ets_flush(Microwaveprop.PromEx.__ets_cron_flusher_name__())
+
         conn
         |> put_resp_content_type("text/plain; version=0.0.4")
         |> send_resp(200, body)