diff --git a/NightLight.Core/PartsOfDay.fs b/NightLight.Core/PartsOfDay.fs
index f50c002..b98aa7a 100644
--- a/NightLight.Core/PartsOfDay.fs
+++ b/NightLight.Core/PartsOfDay.fs
@@ -1,4 +1,4 @@
-module NightLight.PartsOfDay
+module internal NightLight.PartsOfDay
 
 open System