diff --git a/Dockerfile b/Dockerfile
index 2602fb82..f264a26d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -34,8 +34,8 @@ RUN set -eux; \
 # https://getcomposer.org/doc/03-cli.md#composer-allow-superuser
 ENV COMPOSER_ALLOW_SUPERUSER=1
 
-# Transport to use by Mercure (default to Bolt)
-ENV MERCURE_TRANSPORT_URL=bolt:///data/mercure.db
+# Extra directives for Mercure
+ENV MERCURE_EXTRA_DIRECTIVES="transport bolt { path /data/mercure.db }"
 
 ENV PHP_INI_SCAN_DIR=":$PHP_INI_DIR/app.conf.d"
 
diff --git a/compose.override.yaml b/compose.override.yaml
index ed85a3fd..d097384d 100644
--- a/compose.override.yaml
+++ b/compose.override.yaml
@@ -14,7 +14,11 @@ services:
       #- /app/vendor
     environment:
       FRANKENPHP_WORKER_CONFIG: watch
-      MERCURE_EXTRA_DIRECTIVES: demo
+      MERCURE_EXTRA_DIRECTIVES: |-
+        transport bolt {
+          path /data/mercure.db
+        }
+        demo
       # See https://xdebug.org/docs/all_settings#mode
       XDEBUG_MODE: "${XDEBUG_MODE:-off}"
       APP_ENV: "${APP_ENV:-dev}"