diff --git a/lib/aprsme/device_identification.ex b/lib/aprsme/device_identification.ex
index 17bd00c..9ad770e 100644
--- a/lib/aprsme/device_identification.ex
+++ b/lib/aprsme/device_identification.ex
@@ -144,14 +144,18 @@ defmodule Aprsme.DeviceIdentification do
   defp now_for_insert, do: NaiveDateTime.utc_now(:second)
 
   def fetch_and_upsert_devices do
-    case CircuitBreaker.call(:aprs_foundation_api, &fetch_devices_from_url/0, 15_000) do
+    url = Application.get_env(:aprsme, :device_id_url, @url)
+
+    case CircuitBreaker.call(:aprs_foundation_api, fn -> fetch_devices_from_url(url) end, 15_000) do
       {:ok, result} -> result
       {:error, reason} -> {:error, reason}
     end
   end
 
-  defp fetch_devices_from_url do
-    case Req.get(@url) do
+  @doc false
+  # Exposed for testing via URL injection.
+  def fetch_devices_from_url(url \\ @url) do
+    case Req.get(url) do
       {:ok, %Req.Response{status: 200, body: body}} ->
         upsert_devices(body)
 
diff --git a/test/aprsme/device_identification_test.exs b/test/aprsme/device_identification_test.exs
index a2dade6..c092df4 100644
--- a/test/aprsme/device_identification_test.exs
+++ b/test/aprsme/device_identification_test.exs
@@ -203,6 +203,15 @@ defmodule Aprsme.DeviceIdentificationTest do
     end
   end
 
+  describe "fetch_devices_from_url/1 with direct URL" do
+    test "returns an error tuple on non-200 response" do
+      # httpbin.org-style path that returns non-200 is not reliable;
+      # just pass an invalid URL to hit the error branch.
+      result = DeviceIdentification.fetch_devices_from_url("http://invalid.local.test.invalid:1/404")
+      assert match?({:error, _}, result)
+    end
+  end
+
   describe "fetch_and_upsert_devices circuit-breaker path" do
     test "returns an error tuple when circuit breaker rejects or HTTP fails" do
       # This just exercises the fetch_and_upsert_devices path, which runs via
diff --git a/test/aprsme_web/live/map_live/index_test.exs b/test/aprsme_web/live/map_live/index_test.exs
index 0fac729..14a1c7c 100644
--- a/test/aprsme_web/live/map_live/index_test.exs
+++ b/test/aprsme_web/live/map_live/index_test.exs
@@ -4,6 +4,17 @@ defmodule AprsmeWeb.MapLive.IndexTest do
   import Phoenix.ConnTest
   import Phoenix.LiveViewTest
 
+  setup do
+    # Reset the shared Hammer ETS so per-IP request counts don't bleed
+    # between test cases and trigger 429s in the middle of a run.
+    case :ets.info(Aprsme.RateLimiter) do
+      :undefined -> :ok
+      _ -> :ets.delete_all_objects(Aprsme.RateLimiter)
+    end
+
+    :ok
+  end
+
   describe "Index" do
     test "renders map view", %{conn: conn} do
       {:ok, view, html} = live(conn, "/", on_error: :warn)