diff --git a/integration-tests/external-tools-test/docker-compose.yml b/integration-tests/external-tools-test/docker-compose.yml
index 9851c4e..f2de787 100644
--- a/integration-tests/external-tools-test/docker-compose.yml
+++ b/integration-tests/external-tools-test/docker-compose.yml
@@ -3,7 +3,7 @@ services:
   tests:
     hostname: "postfix"
     image: "boky/postfix"
-    restart: no
+    restart: "no"
     volumes:
       - "./tests:/tests"
     environment: