diff --git a/src/openpgp.js b/src/openpgp.js
index 6d6b06d4..495ea9e8 100644
--- a/src/openpgp.js
+++ b/src/openpgp.js
@@ -89,10 +89,12 @@ export function getWorker() {
 /**
  * Cleanup the current instance of the web worker.
  */
-export function destroyWorker() {
-  if (asyncProxy) {
-    asyncProxy.terminate();
-    asyncProxy = undefined;
+export async function destroyWorker() {
+  const proxy = asyncProxy;
+  asyncProxy = undefined;
+  if (proxy) {
+    await proxy.clearKeyCache();
+    proxy.terminate();
   }
 }