diff --git a/lib/sequel/adapters/mysql2.rb b/lib/sequel/adapters/mysql2.rb
index 4da07d7..b2187ce 100644
--- a/lib/sequel/adapters/mysql2.rb
+++ b/lib/sequel/adapters/mysql2.rb
@@ -57,6 +57,7 @@ module Sequel
       def connect(server)
         opts = server_opts(server)
         opts[:host] ||= 'localhost'
+        opts[:username] ||= opts[:user]
         conn = ::Mysql2::Client.new(opts)
 
         sqls = []