The title molecule, C11H13NO2Si, lies on a mirror plane, with only one methyl group lying out of plane. The C[symbol: see text]C triple bond has a length of 1.199 (4) A. Bond angles Si-C[symbol: see text]C and C[symbol: see text]C-C(Ar) are 177.9 (3) and 178.0 (3) degrees, respectively. The Si-Csp3 bond lengths are 1.831 (4) and 1.838 (3) A, while the Si-Csp distance is 1.839 (3) A.