diff --git a/rebar.config b/rebar.config
index 98c7aad..bc423e3 100644
--- a/rebar.config
+++ b/rebar.config
@@ -4,6 +4,8 @@
 {app_bin, ["priv/rebar"]}.
 {escript_shebang, "#!/usr/bin/env escript\n"}.
 {escript_emu_args, "%%! -noshell -noinput\n"}.
+%% escript_incl_extra is for internal rebar-private use only.
+%% Do not use outside rebar. Config interface is not stable.
 {escript_incl_extra, [{"priv/templates/*", "priv/templates"}]}.
 {erl_opts, [warnings_as_errors]}.
 {xref_checks, []}.
diff --git a/src/rebar_escripter.erl b/src/rebar_escripter.erl
index 6139d6e..04fb615 100644
--- a/src/rebar_escripter.erl
+++ b/src/rebar_escripter.erl
@@ -120,7 +120,8 @@ copy_files(Config, AppName, Temp) ->
     %% copy incl_apps files
     lists:foreach(fun(Src) -> ok = copy_files(Src, EbinDir) end, InclEbinDirs),
 
-    %% Look for a list of extra files to copy
+    %% Look for a list of extra files to copy.
+    %% For internal rebar-private use only. Do not use outside rebar.
     InclExtr = rebar_config:get_local(Config, escript_incl_extra, []),
     lists:foreach(fun({Src, Dst}) ->
                           copy_files(Src, filename:join(Temp, Dst))