diff --git a/src/docker.js b/src/docker.js
index a5798a145..0734630b1 100644
--- a/src/docker.js
+++ b/src/docker.js
@@ -574,6 +574,7 @@ async function createSubcontainer(app, name, cmd, options) {
         `CLOUDRON_APP_ORIGIN=https://${domain}`,
         `CLOUDRON_APP_DOMAIN=${domain}`
     ];
+    if (app.debugMode) stdEnv.push('CLOUDRON_DEBUG=1');
 
     if (app.manifest.multiDomain) stdEnv.push(`CLOUDRON_ALIAS_DOMAINS=${app.aliasDomains.map(ad => ad.fqdn).join(',')}`);