diff --git a/lib/appsignal_phoenix/event_handler.ex b/lib/appsignal_phoenix/event_handler.ex
index e3b0653..0252cfc 100644
--- a/lib/appsignal_phoenix/event_handler.ex
+++ b/lib/appsignal_phoenix/event_handler.ex
@@ -106,6 +106,12 @@ defmodule Appsignal.Phoenix.EventHandler do
   def phoenix_template_render_start(_event, _measurements, metadata, _config) do
     parent = @tracer.current_span()
 
+    _ = @span.set_sample_data_if_nil(@tracer.root_span(), "tags", %{
+      "phoenix_template" => metadata.template,
+      "phoenix_format" => metadata.format,
+      "phoenix_view" => module_name(metadata.view)
+    })
+
     "http_request"
     |> @tracer.create_span(parent)
     |> @span.set_name(
diff --git a/test/appsignal_phoenix/event_handler_test.exs b/test/appsignal_phoenix/event_handler_test.exs
index 13cc153..c452820 100644
--- a/test/appsignal_phoenix/event_handler_test.exs
+++ b/test/appsignal_phoenix/event_handler_test.exs
@@ -254,6 +254,18 @@ defmodule Appsignal.Phoenix.EventHandlerTest do
       assert {:ok, [{%Span{}, "appsignal:category", "render.phoenix_template"}]} =
                Test.Span.get(:set_attribute)
     end
+
+    test "sets the root span's tags" do
+      assert {:ok,
+              [
+                {%Span{}, "tags",
+                 %{
+                   "phoenix_template" => "template",
+                   "phoenix_format" => "html",
+                   "phoenix_view" => "PhoenixWeb.View"
+                 }}
+              ]} = Test.Span.get(:set_sample_data_if_nil)
+    end
   end
 
   describe "after receiving an render-start and an render-stop event" do