diff --git a/lib/philomena_web/plugs/user_attribution_plug.ex b/lib/philomena_web/plugs/user_attribution_plug.ex
index f2fb2ed6..bfbd5da8 100644
--- a/lib/philomena_web/plugs/user_attribution_plug.ex
+++ b/lib/philomena_web/plugs/user_attribution_plug.ex
@@ -24,7 +24,7 @@ defmodule PhilomenaWeb.UserAttributionPlug do
     attributes = [
       ip: remote_ip,
       fingerprint: fingerprint(conn, conn.path_info),
-      referrer: conn.assigns.referrer,
+      referrer: referrer(conn.assigns.referrer),
       user: user,
       user_agent: user_agent(conn)
     ]
@@ -47,4 +47,7 @@ defmodule PhilomenaWeb.UserAttributionPlug do
   defp fingerprint(conn, _) do
     conn.cookies["_ses"]
   end
+
+  defp referrer(nil), do: nil
+  defp referrer(r), do: String.slice(r, 0, 255)
 end