diff --git a/lib/ecto/adapters/sql/connection.ex b/lib/ecto/adapters/sql/connection.ex
index a6233f4c..19cc33e4 100644
--- a/lib/ecto/adapters/sql/connection.ex
+++ b/lib/ecto/adapters/sql/connection.ex
@@ -113,5 +113,5 @@ defmodule Ecto.Adapters.SQL.Connection do
   @doc """
   Returns a queryable to check if the given `table` exists.
   """
-  @callback table_exists_query(table :: String.t) :: Ecto.Query.t
+  @callback table_exists_query(table :: String.t) :: {iodata, [term]}
 end