diff --git a/doc/api/modules.markdown b/doc/api/modules.markdown
index bd715f9fecaefc..4c4cacbaf68ac1 100644
--- a/doc/api/modules.markdown
+++ b/doc/api/modules.markdown
@@ -212,6 +212,12 @@ module (loading from `node_modules` folders), it is not a *guarantee*
 that `require('foo')` will always return the exact same object, if it
 would resolve to different files.
 
+Additionally, on case-insensitive file systems or operating systems, different
+resolved filenames can point to the same file, but the cache will still treat
+them as different modules and will reload the file multiple times. For example,
+`require('./foo')` and `require('./FOO')` return two different objects,
+irrespective of whether or not `./foo` and `./FOO` are the same file.
+
 ## Core Modules
 
 <!--type=misc-->