diff --git a/deployment/develop/docker/docker-compose.yaml b/deployment/develop/docker/docker-compose.yaml
index 7e801ff..c42a0ae 100644
--- a/deployment/develop/docker/docker-compose.yaml
+++ b/deployment/develop/docker/docker-compose.yaml
@@ -23,12 +23,15 @@ services:
       timeout: 5s
       retries: 5
     environment:
-      RABBITMQ_DEFAULT_USER: ${RABBITMQ_USER}
-      RABBITMQ_DEFAULT_PASS: ${RABBITMQ_PASSWORD}
+      RABBITMQ_USER: ${RABBITMQ_USER}
+      RABBITMQ_PASSWORD: ${RABBITMQ_PASSWORD}
+    entrypoint: ["/usr/local/bin/docker-entrypoint-wrapper.sh"]
+    command: ["rabbitmq-server"]
     volumes:
+      - ./rabbit/docker-entrypoint-wrapper.sh:/usr/local/bin/docker-entrypoint-wrapper.sh:ro
       - ./rabbitmq_plugins/enabled_plugins:/etc/rabbitmq/enabled_plugins:ro
       - ./rabbit/rabbitmq.conf:/etc/rabbitmq/rabbitmq.conf:ro
-      - ./rabbit/definitions.json:/etc/rabbitmq/definitions.json:ro
+      - ./rabbit/definitions.json:/etc/rabbitmq/definitions.template.json:ro
     networks:
       - internal
       - proxy
diff --git a/deployment/develop/rabbit/definitions.json b/deployment/develop/rabbit/definitions.json
index 50c94d8..d8c3b60 100644
--- a/deployment/develop/rabbit/definitions.json
+++ b/deployment/develop/rabbit/definitions.json
@@ -3,6 +3,13 @@
 	"rabbitmq_version": "4.2.2",
 	"product_name": "RabbitMQ",
 	"product_version": "4.2.2",
+	"users": [
+		{
+			"name": "RABBITMQ_USER_PLACEHOLDER",
+			"password": "RABBITMQ_PASSWORD_PLACEHOLDER",
+			"tags": ["administrator"]
+		}
+	],
 	"vhosts": [
 		{
 			"name": "sim-vhost"
@@ -10,7 +17,7 @@
 	],
 	"permissions": [
 		{
-			"user": "guest",
+			"user": "RABBITMQ_USER_PLACEHOLDER",
 			"vhost": "sim-vhost",
 			"configure": ".*",
 			"write": ".*",
diff --git a/deployment/develop/rabbit/docker-entrypoint-wrapper.sh b/deployment/develop/rabbit/docker-entrypoint-wrapper.sh
new file mode 100755
index 0000000..a960ee7
--- /dev/null
+++ b/deployment/develop/rabbit/docker-entrypoint-wrapper.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+set -eu
+
+# Substitute env vars into definitions template before RabbitMQ starts.
+# RabbitMQ 4.x skips default user creation when definitions.json is loaded,
+# so the user must be defined in the JSON itself.
+sed \
+  -e "s|RABBITMQ_USER_PLACEHOLDER|${RABBITMQ_USER}|g" \
+  -e "s|RABBITMQ_PASSWORD_PLACEHOLDER|${RABBITMQ_PASSWORD}|g" \
+  /etc/rabbitmq/definitions.template.json > /etc/rabbitmq/definitions.json
+
+exec docker-entrypoint.sh "$@"