diff --git a/README.md b/README.md
index 1d146c0..3856416 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,11 @@
 
 Small collection of Docker and Docker Compose files I use to run stuff on my
 personal laptop.
+
+## Notes
+
+- The `mysql` compose file uses a named volume, instead of mounting a directory
+  on the host. This is due to a
+  [bug](https://forums.docker.com/t/posix-fallocate-issues/11370) in the OS X
+  Beta version of Docker. Once the bug is resolved, I'll be mounting a host
+  directory instead.