diff --git a/docker/docker-compose/pigallery2-only/docker-compose.yml b/docker/docker-compose/pigallery2-only/docker-compose.yml
index 94b9cfb8..eceb4808 100644
--- a/docker/docker-compose/pigallery2-only/docker-compose.yml
+++ b/docker/docker-compose/pigallery2-only/docker-compose.yml
@@ -1,4 +1,4 @@
-version: '3'
+version: '3.9'
 services:
   pigallery2:
     image: bpatrik/pigallery2:latest