For an extension A⊆ B of commutative rings, we present a sufficient condition for the ring [[ A S,⩽ ]] of generalized power series to be t-closed in [[ B S,⩽ ]], where ( S,⩽) is a torsion-free cancellative ordered monoid. As a corollary, this result can be applied to the ring of power series in any number of indeterminates.