diff --git a/lib/philomena/conversations/conversation.ex b/lib/philomena/conversations/conversation.ex
index 6e423ac2..19f05266 100644
--- a/lib/philomena/conversations/conversation.ex
+++ b/lib/philomena/conversations/conversation.ex
@@ -48,6 +48,7 @@ defmodule Philomena.Conversations.Conversation do
     |> set_slug()
     |> set_last_message()
     |> cast_assoc(:messages, with: {Message, :creation_changeset, [from]})
+    |> validate_length(:messages, is: 1)
   end
 
   defp set_slug(changeset) do
diff --git a/lib/philomena_web/controllers/conversation_controller.ex b/lib/philomena_web/controllers/conversation_controller.ex
index 047d9cb7..7fcccc7a 100644
--- a/lib/philomena_web/controllers/conversation_controller.ex
+++ b/lib/philomena_web/controllers/conversation_controller.ex
@@ -62,11 +62,7 @@ defmodule PhilomenaWeb.ConversationController do
     render(conn, "new.html", changeset: changeset)
   end
 
-  # Somewhat annoying, cast_assoc has no "limit" validation so we force it
-  # here to require exactly 1
-  def create(conn, %{"conversation" => %{"messages" => %{"0" => message_params} = messages_params} = conversation_params})
-    when %{"0" => message_params} == messages_params
-  do
+  def create(conn, %{"conversation" => conversation_params}) do
     user = conn.assigns.current_user
 
     case Conversations.create_conversation(user, conversation_params) do