diff --git a/libtextsecure/outgoing_message.js b/libtextsecure/outgoing_message.js
index b83a55b5e..2687ebea2 100644
--- a/libtextsecure/outgoing_message.js
+++ b/libtextsecure/outgoing_message.js
@@ -219,12 +219,16 @@ OutgoingMessage.prototype = {
     return this.plaintext;
   },
   async wrapInWebsocketMessage(outgoingObject) {
+    const preKeyEnvelope = outgoingObject.preKeyBundleMessage ? {
+      preKeyBundleMessage: outgoingObject.preKeyBundleMessage,
+    } : {};
     const messageEnvelope = new textsecure.protobuf.Envelope({
       type: outgoingObject.type,
       source: outgoingObject.ourKey,
       sourceDevice: outgoingObject.sourceDevice,
       timestamp: this.timestamp,
       content: outgoingObject.content,
+      ...preKeyEnvelope,
     });
     const requestMessage = new textsecure.protobuf.WebSocketRequestMessage({
       id: new Uint8Array(libsignal.crypto.getRandomBytes(1))[0], // random ID for now
diff --git a/protos/SignalService.proto b/protos/SignalService.proto
index 5e2b905de..ecf9743d1 100644
--- a/protos/SignalService.proto
+++ b/protos/SignalService.proto
@@ -24,7 +24,7 @@ message Envelope {
   optional bytes  content         = 8; // Contains an encrypted Content
   optional string serverGuid      = 9;
   optional uint64 serverTimestamp = 10;
-  optional PreKeyBundleMessage preKeyBundleMessage = 101;
+  optional bytes preKeyBundleMessage = 101;
 
 }