The CP asymmetry in the mixing of B0s and ¯B0s mesons is measured in proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1, recorded by the LHCb experiment at center-of-mass energies of 7 and 8 TeV. Semileptonic B0s and ¯B0s decays are studied in the inclusive mode D∓sμ±(−)νμX with the D∓s mesons reconstructed in the K+K−π∓ final state. Correcting the observed charge asymmetry for detection and background effects, the CP asymmetry is found to be assl=(0.39±0.26±0.20)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of assl to date. It is consistent with the prediction from the standard model and will constrain new models of particle physics.Received 1 June 2016Corrected 15 March 2017DOI:https://doi.org/10.1103/PhysRevLett.117.061803Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.© 2016 CERN, for the LHCb CollaborationPhysics Subject Headings (PhySH)Research AreasHadron mixingPhysical SystemsBottom mesonsPropertiesCP violationParticles & Fields