diff --git a/README.md b/README.md
index 86620de0ed82b6b659b6eb99815e6a40d53970ca..a804697fb592e356f1bac3f7e88bc59286c89cff 100644
--- a/README.md
+++ b/README.md
@@ -144,3 +144,4 @@ Yjs is licensed under the [MIT License](./LICENSE.txt).
 
 [ShareJs]: https://github.com/share/ShareJS
 [OpenCoweb]: https://github.com/opencoweb/coweb/wiki
+
diff --git a/dist b/dist
index 8ba1e4ce27a75bb025a5478723ea57f7f437ccf0..ab6a193ec6ec799bdb77fa23eeec1f05d5b910d6 160000
--- a/dist
+++ b/dist
@@ -1 +1 @@
-Subproject commit 8ba1e4ce27a75bb025a5478723ea57f7f437ccf0
+Subproject commit ab6a193ec6ec799bdb77fa23eeec1f05d5b910d6
diff --git a/src/Connector.js b/src/Connector.js
index 0a1bb4e1c053bdc12b20ddc3ce3fe00d02a0b4cd..bc55ccf2c323f6139642a2bcdfa8ae3f9a47643b 100644
--- a/src/Connector.js
+++ b/src/Connector.js
@@ -63,8 +63,12 @@ module.exports = function (Y/* :any */) {
       return this.y.db.stopGarbageCollector()
     }
     setUserId (userId) {
-      this.userId = userId
-      return this.y.db.setUserId(userId)
+      if (this.userId == null) {
+        this.userId = userId
+        return this.y.db.setUserId(userId)
+      } else {
+        return null
+      }
     }
     onUserEvent (f) {
       this.userEventListeners.push(f)