  In this note self-adjoint extensions of symmetric operators are investigated
by using the abstract technique of quasi boundary triples and their Weyl
functions. The main result is an extension of Theorem 2.6 in [5] which provides
sufficient conditions on the parameter in the boundary space to induce
self-adjoint realizations. As an example self-adjoint Robin Laplacians on the
half-space with boundary conditions involving an unbounded coefficient are
considered.
