diff --git a/lib/phoenix/config.ex b/lib/phoenix/config.ex
index fc9ed22ed9..3b6dde435e 100644
--- a/lib/phoenix/config.ex
+++ b/lib/phoenix/config.ex
@@ -20,8 +20,8 @@ defmodule Phoenix.Config do
   @doc """
   Puts a given key-value pair in config.
   """
-  def put_new(module, key, value) do
-    :ets.insert_new(module, {key, value})
+  def put(module, key, value) do
+    :ets.insert(module, {key, value})
   end
 
   @doc """
diff --git a/lib/phoenix/endpoint/supervisor.ex b/lib/phoenix/endpoint/supervisor.ex
index f8d315dbd4..253db8c9cb 100644
--- a/lib/phoenix/endpoint/supervisor.ex
+++ b/lib/phoenix/endpoint/supervisor.ex
@@ -381,7 +381,7 @@ defmodule Phoenix.Endpoint.Supervisor do
   end
 
   defp warmup_static(endpoint, %{"latest" => latest, "digests" => digests}) do
-    Phoenix.Config.put_new(endpoint, :cache_static_manifest_latest, latest)
+    Phoenix.Config.put(endpoint, :cache_static_manifest_latest, latest)
     with_vsn? = !endpoint.config(:cache_manifest_skip_vsn)
 
     Enum.each(latest, fn {key, _} ->