diff --git a/src/openpgp.js b/src/openpgp.js
index 6a7aa6ed..612d05c2 100644
--- a/src/openpgp.js
+++ b/src/openpgp.js
@@ -235,7 +235,7 @@ export function encrypt({ data, publicKeys, privateKeys, passwords, sessionKey,
   checkData(data); publicKeys = toArray(publicKeys); privateKeys = toArray(privateKeys); passwords = toArray(passwords);
 
   if (!nativeAEAD() && asyncProxy) { // use web worker if web crypto apis are not supported
-    return asyncProxy.delegate('encrypt', { data, publicKeys, privateKeys, passwords, sessionKey, filename, armor, detached, signature, returnSessionKey, wildcard, date });
+    return asyncProxy.delegate('encrypt', { data, publicKeys, privateKeys, passwords, sessionKey, filename, compression, armor, detached, signature, returnSessionKey, wildcard, date });
   }
   const result = {};
   return Promise.resolve().then(async function() {