diff --git a/src/npserv/Database/ISession.cs b/src/npserv/Database/ISession.cs
index c77f182..272e522 100644
--- a/src/npserv/Database/ISession.cs
+++ b/src/npserv/Database/ISession.cs
@@ -6,6 +6,7 @@ namespace NPSharp.CommandLine.Server.Database
     [Entity]
     public interface ISession
     {
+        [Identifier]
         string Id { get; }
 
         IUser User { get; }
diff --git a/src/npserv/Database/IUser.cs b/src/npserv/Database/IUser.cs
index 35a0fd0..7e1e033 100644
--- a/src/npserv/Database/IUser.cs
+++ b/src/npserv/Database/IUser.cs
@@ -7,6 +7,7 @@ namespace NPSharp.CommandLine.Server.Database
     [Entity]
     public interface IUser
     {
+        [Identifier]
         string Id { get; }
 
         string UserName { get; set; }