diff --git a/src/ServiceStack.Aws/DynamoDb/DynamoDbAuthRepository.cs b/src/ServiceStack.Aws/DynamoDb/DynamoDbAuthRepository.cs
index 2996424a..2eeb6b31 100644
--- a/src/ServiceStack.Aws/DynamoDb/DynamoDbAuthRepository.cs
+++ b/src/ServiceStack.Aws/DynamoDb/DynamoDbAuthRepository.cs
@@ -159,6 +159,9 @@ private void Sanitize(IUserAuth userAuth)
 
         private IUserAuth DeSanitize(TUserAuth userAuth)
         {
+            if (userAuth == null)
+                return null;
+            
             if (userAuth.UserName != null && userAuth.UserName.Contains("@"))
             {
                 if (userAuth.Email == null)