diff --git a/docker-compose.master.yml b/docker-compose.master.yml
index db4525c..cce0c96 100644
--- a/docker-compose.master.yml
+++ b/docker-compose.master.yml
@@ -79,7 +79,9 @@ services:
     image: jonasal/nginx-certbot:latest
     restart: always
     environment:
-      - CERTBOT_EMAIL
+      CERTBOT_EMAIL: ${CERTBOT_EMAIL}
+      DHPARAM_SIZE: 4096
+      RSA_KEY_SIZE: 4096
     env_file:
       - ./nginx-certbot.env
     ports:
diff --git a/docker-compose.slave.yml b/docker-compose.slave.yml
index b0db405..fd52f53 100644
--- a/docker-compose.slave.yml
+++ b/docker-compose.slave.yml
@@ -56,7 +56,9 @@ services:
     image: jonasal/nginx-certbot:latest
     restart: always
     environment:
-      - CERTBOT_EMAIL
+      CERTBOT_EMAIL: ${CERTBOT_EMAIL}
+      DHPARAM_SIZE: 4096
+      RSA_KEY_SIZE: 4096
     env_file:
       - ./nginx-certbot.env
     ports: