diff --git a/gmcapsule/gemini.py b/gmcapsule/gemini.py

index 4744387..ce4edd2 100644

--- a/gmcapsule/gemini.py

+++ b/gmcapsule/gemini.py

@@ -252,6 +252,10 @@ class Cache:

 Cache objects have been installed, the save/load operation is attempted

 on each in turn until one cache succeeds in saving or loading content.



+ Each server worker thread constructs their own Cache objects. If there

+ is a shared backing store like a file system or a database, proper care

+ should be taken to synchronize access to it from the Cache objects.

+

 The mapping from URLs to cache paths is::



     gemini://example.com/path/file.gmi