diff --git a/lib/towerops_web/live/site_live/show.ex b/lib/towerops_web/live/site_live/show.ex
index e5a35aab..c5d8b0a9 100644
--- a/lib/towerops_web/live/site_live/show.ex
+++ b/lib/towerops_web/live/site_live/show.ex
@@ -172,8 +172,9 @@ defmodule ToweropsWeb.SiteLive.Show do
   end
 
   defp format_response_time(nil), do: "—"
-  defp format_response_time(ms) when ms < 1, do: "<1ms"
-  defp format_response_time(ms), do: "#{round(ms)}ms"
+  defp format_response_time(ms) when is_number(ms) and ms < 1, do: "<1ms"
+  defp format_response_time(ms) when is_number(ms), do: "#{round(ms)}ms"
+  defp format_response_time(_), do: "—"
 
   defp change_size_label(size) when size < 100, do: "Small"
   defp change_size_label(size) when size < 500, do: "Medium"