SQLite Versioning Configuration Question

I am trying to use SQLite (version 3 in-memory db) within my
integration tests, but my tests consistenly fail throwing the
following message:

System.Data.SQLite.SQLiteException : Abort due to constraint violation
Version may not be NULL

I have mapped a very simple object using optimistic concurrency as
follows:

Id(x => x.Id).GeneratedBy.GuidComb(); ... OptimisticLock.Version(); Version(x => x.Version)

          .Column("Version")
          .UnsavedValue("null")
          .CustomSqlType("timestamp")
          .Generated.Always();

When I run my tests against MS SQL Server, the insert statement that
is generated does not pass a value for the 'Version' field. SQLServer
creates a binary value and inserts that value into the 'Version' field
automatically.

When I try to run my tests against my SQLite in-memory db, however,
the binary value is not auto-generated by SQLite. (which leads to the
aforementioned exception)

Is there any way to map an object so that the Version field auto
generates a binary value for both MS SQL Server and SQLite? Any help
is MUCH appreciated!