diff --git a/init.sql b/init.sql
index dd11655..e75cdb2 100644
--- a/init.sql
+++ b/init.sql
@@ -31,7 +31,7 @@ CREATE INDEX IDX_session_expire ON sessions(expire);
 -- Création de la table users
 CREATE TABLE users (
   id VARCHAR PRIMARY KEY NOT NULL,
-  username VARCHAR UNIQUE,
+  username VARCHAR UNIQUE NOT NULL,
   email VARCHAR UNIQUE,
   name VARCHAR,
   first_name VARCHAR,
diff --git a/shared/schema.ts b/shared/schema.ts
index a38f52a..cb09e89 100644
--- a/shared/schema.ts
+++ b/shared/schema.ts
@@ -30,7 +30,7 @@ export const sessions = pgTable(
 // User storage table - supports both Replit Auth and local auth
 export const users = pgTable("users", {
   id: varchar("id").primaryKey().notNull(),
-  username: varchar("username").unique(), // For simple login
+  username: varchar("username").unique().notNull(), // For simple login
   email: varchar("email").unique(),
   name: varchar("name"), // Single name field for compatibility
   firstName: varchar("first_name"),