diff --git a/docker/web-demo.yml b/docker/web-demo.yml
index 633d71df..505a0f26 100644
--- a/docker/web-demo.yml
+++ b/docker/web-demo.yml
@@ -6,8 +6,9 @@ services:
     depends_on:
       # we need to depend on backend to get IP address of the container for conf
       - backend
-    tmpfs: /var/lib/prosody
-    tmpfs: /var/log/prosody
+    tmpfs:
+      - /var/lib/prosody
+      - /var/log/prosody
     networks:
       default:
         aliases: