diff --git a/README.md b/README.md
index d06533c..c344e17 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,7 @@ following Mix config:
 ```elixir
 config :briefly,
   directory: [{:system, "TMPDIR"}, {:system, "TMP"}, {:system, "TEMP"}, "/tmp"],
+  sub_directory_prefix: "briefly",
   default_prefix: "briefly",
   default_extname: ""
   ```
diff --git a/lib/briefly/config.ex b/lib/briefly/config.ex
index 7b7d0d2..3724e37 100644
--- a/lib/briefly/config.ex
+++ b/lib/briefly/config.ex
@@ -3,6 +3,8 @@ defmodule Briefly.Config do
 
   def directory, do: get(:directory)
 
+  def sub_directory_prefix, do: get(:sub_directory_prefix)
+
   def default_prefix, do: get(:default_prefix)
 
   def default_extname, do: get(:default_extname)
diff --git a/lib/briefly/entry.ex b/lib/briefly/entry.ex
index 211d717..8b27e86 100644
--- a/lib/briefly/entry.ex
+++ b/lib/briefly/entry.ex
@@ -18,9 +18,10 @@ defmodule Briefly.Entry do
 
   def init(_init_arg) do
     tmp = Briefly.Config.directory()
+    sub = Briefly.Config.sub_directory_prefix()
     cwd = Path.join(File.cwd!(), "tmp")
     ets = :ets.new(:briefly, [:private])
-    {:ok, {[tmp, cwd], ets}}
+    {:ok, {[tmp, cwd, sub], ets}}
   end
 
   def handle_call({:create, opts}, {caller_pid, _ref}, {tmps, ets} = state) do
@@ -68,8 +69,9 @@ defmodule Briefly.Entry do
 
   defp ensure_tmp_dir(tmps) do
     {mega, _, _} = :os.timestamp()
-    subdir = "briefly-" <> i(mega)
-    Enum.find_value(tmps, &write_tmp_dir(&1 <> subdir))
+    [_tmp, _cwd, sub] = tmps
+    subdir = "#{sub}-#{mega}"
+    Enum.find_value(tmps, &write_tmp_dir(Path.join(&1, subdir)))
   end
 
   defp write_tmp_dir(path) do
@@ -110,9 +112,6 @@ defmodule Briefly.Entry do
     {:too_many_attempts, tmp, attempts}
   end
 
-  @compile {:inline, i: 1}
-  defp i(integer), do: Integer.to_string(integer)
-
   defp path(options, tmp) do
     time = :erlang.monotonic_time() |> to_string |> String.trim("-")
 
diff --git a/mix.exs b/mix.exs
index 6cfbdf7..6279ca9 100644
--- a/mix.exs
+++ b/mix.exs
@@ -49,6 +49,7 @@ defmodule Briefly.Mixfile do
   defp default_env do
     [
       directory: [{:system, "TMPDIR"}, {:system, "TMP"}, {:system, "TEMP"}, "/tmp"],
+      sub_directory_prefix: "briefly",
       default_prefix: "briefly",
       default_extname: ""
     ]