diff --git a/mo/db.py b/mo/db.py
index 7f3a40883db01dbd0152990fd9303815881f9b83..1b3e5ff9fe2c8d728718de6f5b3e7f7ae40fbf06 100644
--- a/mo/db.py
+++ b/mo/db.py
@@ -249,7 +249,7 @@ class Round(Base):
     seq = Column(Integer, nullable=False)
     part = Column(Integer, nullable=False)
     level = Column(Integer, nullable=False)
-    code = Column(String(255), nullable=False)
+    code = Column(String(255), nullable=False, server_default=text("''::text"))
     name = Column(String(255), nullable=False)
     state = Column(Enum(RoundState, name='round_state'), nullable=False, server_default=text("'preparing'::round_state"))
     tasks_file = Column(String(255))