diff --git a/docker-compose.yml b/docker-compose.yml
index 6e4c88a8..5d61471b 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,4 +1,4 @@
-version: '2.3'
+version: '2.1'
 services:
 
     unbound-mailcow: