diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/XiaomiAuthService.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/XiaomiAuthService.java
index cf73f8664..350a74ccb 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/XiaomiAuthService.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/XiaomiAuthService.java
@@ -61,6 +61,8 @@ public class XiaomiAuthService extends AbstractXiaomiService {
 
     public static final int COMMAND_TYPE = 1;
 
+    public static final int CMD_SEND_USERID = 5;
+
     public static final int CMD_NONCE = 26;
     public static final int CMD_AUTH = 27;
 
diff --git a/app/src/main/proto/xiaomi.proto b/app/src/main/proto/xiaomi.proto
index 4daaa0f2c..f6fd63c1e 100644
--- a/app/src/main/proto/xiaomi.proto
+++ b/app/src/main/proto/xiaomi.proto
@@ -29,6 +29,7 @@ message Command {
 //
 
 message Auth {
+  optional string userId = 7;
   // 1, 26
   optional PhoneNonce phoneNonce = 30;
   optional WatchNonce watchNonce = 31;