diff --git a/lib/chronoscope_web/controllers/api/v1/nts/key_establishment_controller.ex b/lib/chronoscope_web/controllers/api/v1/nts/key_establishment_controller.ex
index 8baf4d1..3892e07 100644
--- a/lib/chronoscope_web/controllers/api/v1/nts/key_establishment_controller.ex
+++ b/lib/chronoscope_web/controllers/api/v1/nts/key_establishment_controller.ex
@@ -7,23 +7,23 @@ defmodule ChronoscopeWeb.API.V1.NTS.KeyEstablishmentController do
 
   @default_port 4460
 
-  def get(conn, %{"host" => _, "port" => port} = params) do
+  def get(conn, %{"host" => host, "port" => port}) do
     try do
-      handle_get(conn, Map.put(params, "port", String.to_integer(port)))
+      handle_get(conn, %{host: host, port: String.to_integer(port)})
     rescue
       ArgumentError -> bad_request_response(conn, "invalid port")
     end
   end
 
-  def get(conn, %{"host" => _} = params) do
-    handle_get(conn, Map.put(params, "port", @default_port))
+  def get(conn, %{"host" => host}) do
+    handle_get(conn, %{host: host, port: @default_port})
   end
 
   def get(conn, _params) do
     bad_request_response(conn, "missing host")
   end
 
-  defp handle_get(conn, %{"host" => host, "port" => port}) when is_integer(port) and port > 0 and port < 65536 do
+  defp handle_get(conn, %{host: host, port: port}) when port > 0 and port < 65536 do
     case nts_behaviour().key_establishment(host, port) do
       {:ok, response} ->
         json(conn, %{status: :ok, response: format_response(response)})
@@ -34,7 +34,7 @@ defmodule ChronoscopeWeb.API.V1.NTS.KeyEstablishmentController do
   end
 
   defp handle_get(conn, _params) do
-    bad_request_response(conn, "invalid port")
+    bad_request_response(conn, "port out of range")
   end
 
   defp format_response(response) do
diff --git a/test/chronoscope_web/controllers/api/v1/nts/key_establishment_controller_test.exs b/test/chronoscope_web/controllers/api/v1/nts/key_establishment_controller_test.exs
index 416dd5b..c86b993 100644
--- a/test/chronoscope_web/controllers/api/v1/nts/key_establishment_controller_test.exs
+++ b/test/chronoscope_web/controllers/api/v1/nts/key_establishment_controller_test.exs
@@ -32,7 +32,7 @@ defmodule ChronoscopeWeb.API.V1.NTS.KeyEstablishmentControllerTest do
       |> get(~p"/api/v1/nts/key-establishment?host=localhost&port=65536")
       |> json_response(400)
 
-    assert %{"error" => "invalid port"} == response
+    assert %{"error" => "port out of range"} == response
   end
 
   test "handles a negative port number", %{conn: conn} do
@@ -41,7 +41,7 @@ defmodule ChronoscopeWeb.API.V1.NTS.KeyEstablishmentControllerTest do
       |> get(~p"/api/v1/nts/key-establishment?host=localhost&port=-4460")
       |> json_response(400)
 
-    assert %{"error" => "invalid port"} == response
+    assert %{"error" => "port out of range"} == response
   end
 
   test "handles a bad port number", %{conn: conn} do