  We prove the existence of solution in a class H^2(\Omega) x H^1(\Omega) to
steady compressible Oseen system with slip boundary conditions in a two
dimensional, convex domain with the boundary of class H^{5/2}. The method is to
regularize a weak solution obtained via the Galerkin method. The problem of
regularization is reduced to a problem of solvability of a certain transport
equation by application of the Helmholtz decomposition. The method works under
additional assumption on the geometry of the boundary.
