diff --git a/docker-compose_prod.yml b/docker-compose_prod.yml
index d992c4a..78fe05b 100644
--- a/docker-compose_prod.yml
+++ b/docker-compose_prod.yml
@@ -43,7 +43,7 @@ services:
     env_file: docker/captcha-app/.env
     environment:
       CONTAINER_ROLE: app
-      UNIT_SOURCE: '["172.16.0.0/12"]'
+      UNIT_SOURCE: '"172.16.0.0/12"'
 
   captcha-queue:
     image: korelf/service-captcha:0.8.2