diff --git a/src/matrix/e2ee/OlmWorker.js b/src/matrix/e2ee/OlmWorker.js
index 649db309..e538dd31 100644
--- a/src/matrix/e2ee/OlmWorker.js
+++ b/src/matrix/e2ee/OlmWorker.js
@@ -37,9 +37,15 @@ export class OlmWorker {
         account.unpickle("", pickle);
     }
 
-    async createOutboundSession(account, newSession, theirIdentityKey, theirOneTimeKey) {
+    async createOutboundOlmSession(account, newSession, theirIdentityKey, theirOneTimeKey) {
         const accountPickle = account.pickle("");
-        const sessionPickle = await this._workerPool.send({type: "olm_create_outbound", accountPickle, theirIdentityKey, theirOneTimeKey}).response();
+        let randomValues;
+        if (window.msCrypto) {
+            randomValues = [
+                window.msCrypto.getRandomValues(new Uint8Array(64)),
+            ];
+        }
+        const sessionPickle = await this._workerPool.send({type: "olm_create_outbound", accountPickle, theirIdentityKey, theirOneTimeKey, randomValues}).response();
         newSession.unpickle("", sessionPickle);
     }
 
diff --git a/src/platform/web/worker/main.js b/src/platform/web/worker/main.js
index ae440f57..db8d84e9 100644
--- a/src/platform/web/worker/main.js
+++ b/src/platform/web/worker/main.js
@@ -142,13 +142,14 @@ class MessageHandler {
         });
     }
 
-    _olmCreateOutbound(accountPickle, theirIdentityKey, theirOneTimeKey) {
+    _olmCreateOutbound(randomValues, accountPickle, theirIdentityKey, theirOneTimeKey) {
         return this._toMessage(() => {
+            this._feedRandomValues(randomValues);
             const account = new this._olm.Account();
             const newSession = new this._olm.Session();
             try {
                 account.unpickle("", accountPickle);
-                newSession.create_outbound(account, newSession, theirIdentityKey, theirOneTimeKey);
+                newSession.create_outbound(account, theirIdentityKey, theirOneTimeKey);
                 return newSession.pickle("");
             } finally {
                 account.free();
@@ -168,7 +169,7 @@ class MessageHandler {
         } else if (type === "olm_create_account_otks") {
             this._sendReply(message, this._olmCreateAccountAndOTKs(message.randomValues, message.otkAmount));
         } else if (type === "olm_create_outbound") {
-            this._sendReply(message, this._olmCreateOutbound(message.accountPickle, message.theirIdentityKey, message.theirOneTimeKey));
+            this._sendReply(message, this._olmCreateOutbound(message.randomValues, message.accountPickle, message.theirIdentityKey, message.theirOneTimeKey));
         }
     }
 }