diff --git a/docker-compose.yml b/docker-compose.yml
index 3b2959d5..e3bd8c05 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -8,7 +8,7 @@
 # Documentation:
 #     https://github.com/ArchiveBox/ArchiveBox/wiki/Docker#docker-compose
 
-version: '2.4'
+version: '2.4'   # '3.9' or greater also works
 
 services:
     archivebox: