diff --git a/docker-compose.dev.yml b/docker-compose.dev.yml
index 26fdc84..719de55 100644
--- a/docker-compose.dev.yml
+++ b/docker-compose.dev.yml
@@ -29,6 +29,8 @@ services:
     image: DOCKER_REGISTRY_REPO-ical # DOCKER_REGISTRY_REPO will be replaced by CI
     pull_policy: always
     restart: always
+    environment:
+      - DATA_MANAGER_URL=htwkalender-data-manager
     networks:
       - "net"
 
diff --git a/docker-compose.prod.yml b/docker-compose.prod.yml
index 8358f31..f52e1aa 100644
--- a/docker-compose.prod.yml
+++ b/docker-compose.prod.yml
@@ -29,6 +29,8 @@ services:
     image: DOCKER_REGISTRY_REPO-ical # DOCKER_REGISTRY_REPO will be replaced by CI
     pull_policy: always
     restart: always
+    environment:
+      - DATA_MANAGER_URL=htwkalender-data-manager
     networks:
       - "net"