diff --git a/inbucket/docker-compose.yml b/inbucket/docker-compose.yml
index d33dfcc..58dfe71 100644
--- a/inbucket/docker-compose.yml
+++ b/inbucket/docker-compose.yml
@@ -1,3 +1,5 @@
+version: '3.7'
+
 services:
   inbucket:
     image: inbucket/inbucket:latest