The momentum spectra of K + produced at small angles in proton-proton and proton-deuteron collisions have been measured at four beam energies, 1.826, 1.920, 2.020, and 2.650 GeV, using the ANKE spectrometer at COSY-Jülich. After making corrections for Fermi motion and shadowing, the data indicate that K + production near threshold is stronger in ppthan in pn-induced reactions. However, most of this difference could be made up by the unobserved K 0 production in the pn case.