diff --git a/src/Exceptions.php b/src/Exceptions.php
index 965c226..2fbbf3f 100644
--- a/src/Exceptions.php
+++ b/src/Exceptions.php
@@ -12,6 +12,8 @@ class AuthException extends \Exception {}
 
 class InvalidEmailException extends AuthException {}
 
+class UnknownUsernameException extends AuthException {}
+
 class InvalidPasswordException extends AuthException {}
 
 class EmailNotVerifiedException extends AuthException {}