diff --git a/docker-compose.yml b/docker-compose.yml
index b58854b29..c746f2afb 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -43,5 +43,5 @@ services:
     extends:
       service: create
     environment:
-      PREVENT_CREATE: true
+      PREVENT_CREATE: 'true'
       TOX_REPORT_NAME: tobiko_results_verify