diff --git a/README.md b/README.md
index 19944bee..8150e466 100644
--- a/README.md
+++ b/README.md
@@ -59,7 +59,13 @@ fn main() {
 - Windows: ReadDirectoryChangesW
 - All platforms: polling
 
-### Todo
+## Limitations
+
+### FSEvent
+
+Due to the inner security model of FSEvent (see [FileSystemEventSecurity](https://developer.apple.com/library/mac/documentation/Darwin/Conceptual/FSEvents_ProgGuide/FileSystemEventSecurity/FileSystemEventSecurity.html)), some event cannot be observed easily when trying to follow files that do not belong to you. In this case, reverting to the pollwatcher can fix the issue, with a slight performance cost.
+
+## Todo
 
 - BSD / OS X / iOS: kqueue
 - Solaris 11: FEN