diff --git a/README.md b/README.md
index 0b93d3f..dc673ad 100644
--- a/README.md
+++ b/README.md
@@ -21,3 +21,4 @@
 version is configured with a service graph that includes
 `ExampleService`, which is a good platform for understanding how to
 build and use XOS.
+
diff --git a/xos/core/models/user.py b/xos/core/models/user.py
index e4306c5..d8dd616 100644
--- a/xos/core/models/user.py
+++ b/xos/core/models/user.py
@@ -299,7 +299,8 @@
         if (caller_kind!="synchronizer") or always_update_timestamp:
             self.updated = timezone.now()
 
-        self.username = self.email
+        if not self.username:
+            self.username = self.email
 
         super(User, self).save(*args, **kwargs)