diff --git a/src/docker.js b/src/docker.js
index 1456c4975..a109eacf9 100644
--- a/src/docker.js
+++ b/src/docker.js
@@ -279,6 +279,8 @@ async function createSubcontainer(app, name, cmd, options) {
         `CLOUDRON_APP_DOMAIN=${domain}`
     ];
 
+    const secondaryDomainsEnv = app.secondaryDomains.map(sd => `${sd.environmentVariable}=${sd.fqdn}`);
+
     const portEnv = [];
     for (const portName in app.portBindings) {
         const hostPort = app.portBindings[portName];
@@ -313,7 +315,7 @@ async function createSubcontainer(app, name, cmd, options) {
         Tty: isAppContainer,
         Image: app.manifest.dockerImage,
         Cmd: (isAppContainer && app.debugMode && app.debugMode.cmd) ? app.debugMode.cmd : cmd,
-        Env: stdEnv.concat(addonEnv).concat(portEnv).concat(appEnv),
+        Env: stdEnv.concat(addonEnv).concat(portEnv).concat(appEnv).concat(secondaryDomainsEnv),
         ExposedPorts: isAppContainer ? exposedPorts : { },
         Volumes: { // see also ReadonlyRootfs
             '/tmp': {},