diff --git a/firmware/mix.lock b/firmware/mix.lock
index bfd2a0b..872ef09 100644
--- a/firmware/mix.lock
+++ b/firmware/mix.lock
@@ -39,6 +39,7 @@
   "phoenix_ecto": {:hex, :phoenix_ecto, "4.0.0", "c43117a136e7399ea04ecaac73f8f23ee0ffe3e07acfcb8062fe5f4c9f0f6531", [:mix], [{:ecto, "~> 3.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.9", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
   "phoenix_html": {:hex, :phoenix_html, "2.13.3", "850e292ff6e204257f5f9c4c54a8cb1f6fbc16ed53d360c2b780a3d0ba333867", [:mix], [{:plug, "~> 1.5", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
   "phoenix_live_reload": {:hex, :phoenix_live_reload, "1.2.1", "274a4b07c4adbdd7785d45a8b0bb57634d0b4f45b18d2c508b26c0344bd59b8f", [:mix], [{:file_system, "~> 0.2.1 or ~> 0.3", [hex: :file_system, repo: "hexpm", optional: false]}, {:phoenix, "~> 1.4", [hex: :phoenix, repo: "hexpm", optional: false]}], "hexpm"},
+  "phoenix_live_view": {:hex, :phoenix_live_view, "0.3.1", "5474c9e70db4e5bb23c1d1200d9a119ee76b927f3352554d31f5f31eaa1ea568", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix, "~> 1.4.9", [hex: :phoenix, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.13.2", [hex: :phoenix_html, repo: "hexpm", optional: false]}], "hexpm"},
   "phoenix_pubsub": {:hex, :phoenix_pubsub, "1.1.2", "496c303bdf1b2e98a9d26e89af5bba3ab487ba3a3735f74bf1f4064d2a845a3e", [:mix], [], "hexpm"},
   "plug": {:hex, :plug, "1.8.2", "0bcce1daa420f189a6491f3940cc77ea7fb1919761175c9c3b59800d897440fc", [:mix], [{:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm"},
   "plug_cowboy": {:hex, :plug_cowboy, "2.1.0", "b75768153c3a8a9e8039d4b25bb9b14efbc58e9c4a6e6a270abff1cd30cbe320", [:mix], [{:cowboy, "~> 2.5", [hex: :cowboy, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
diff --git a/morse/lib/morse/worker.ex b/morse/lib/morse/worker.ex
index 467a200..c7b8831 100644
--- a/morse/lib/morse/worker.ex
+++ b/morse/lib/morse/worker.ex
@@ -3,6 +3,8 @@ defmodule Morse.Worker do
   Functions to control the signal lamp connected with GPIO.
   """
 
+  @esrom_node :"esrom@esrom.lan"
+
   @sleep_short 200
   @sleep_delay 400
   @sleep_long 700
@@ -60,10 +62,14 @@ defmodule Morse.Worker do
     |> String.to_charlist()
   end
 
+  # Communicate with a deployed esrom node, if running on a host.
   case Application.get_env(:ui, :target) do
     :host ->
       def toggle_lamp(state) do
-        :rpc.call(:"esrom@esrom.lan", Morse.Worker, :toggle_lamp, [state])
+        # Check if the deployed esrom node is online.
+        if :pong == Node.ping(@esrom_node) do
+          :rpc.call(@esrom_node, Morse.Worker, :toggle_lamp, [state])
+        end
       end
 
     _ ->
diff --git a/ui/lib/ui/application.ex b/ui/lib/ui/application.ex
index 9d75bba..cdef571 100644
--- a/ui/lib/ui/application.ex
+++ b/ui/lib/ui/application.ex
@@ -23,7 +23,7 @@ defmodule Ui.Application do
   def children(:host) do
     {:ok, _} = Node.start(:"host@0.0.0.0")
     Node.set_cookie(:tastycookie)
-    true = Node.connect(:"esrom@esrom.lan")
+    Node.connect(:"esrom@esrom.lan")
     []
   end