The cross section for the production of single top quarks in the t channel is measured in proton-proton collisions at 13 TeV with the CMS detector at the LHC. The analyzed data correspond to an integrated luminosity of View the MathML source2.3fb−1. The event selection requires one muon and two jets where one of the jets is identified as originating from a bottom quark. Several kinematic variables are then combined into a multivariate discriminator to distinguish signal from background events. A fit to the distribution of the discriminating variable yields a total cross section of View the MathML source232±13(stat)±28(syst)pb and a ratio of top quark and top antiquark production of View the MathML sourceRt-ch.=1.81±0.18(stat)±0.15(syst). From the total cross section the absolute value of the CKM matrix element VtbVtb is calculated to be View the MathML source1.03±0.07(exp)±0.02(theo). All results are in agreement with the standard model predictions.