A compound of the formula: or a pharmaceutically acceptable salt thereof, for use in the treatment of an alcohol use disorder; wherein A is or R 1 is fluoro or chloro; R 2a and R 2b are each hydrogen or are each fluoro; R 3 is hydrogen, methyl, hydroxymethyl, or (C 1 -C 3) alkoxymethyl; R 4 is selected from the group consisting of fluoro, chloro, cyano, cyanomethyl, (C 1 -C 3) alkyl, cyclopropyl, hydroxymethyl, methoxy, cyclopropylmethoxy, aminocarbonylmethoxy, (C 1 -C 3) alkoxymethyl, cyclopropyloxymethyl, cyclopropylmethoxymethyl, 1-hydroxy-1-methylethyl, aminocarbonyloxymethyl, methylaminocarbonyloxymethyl, dimethylaminocarbonyloxymethyl, aminocarbonyl, aminocarbonylmethyl, -CH 2 -NR 5 R 6, hydroxyimine, methoxyimine, morpholin-4-yl, morpholin-4-ylmethyl, Ar 1, -CH 2 Ar 1, tetrahydrofuran-2-yl, 3-oxomorpholin-4-ylmethyl, 2-oxopyrrolidin-1-ylmethyl, and 2-oxopiperidin-1-ylmethyl; R 4' is selected from the group consisting of fluoro, chloro, cyano, cyanomethyl, (C 1 -C 3) alkyl, cyclopropyl, hydroxymethyl, methoxy, methoxymethyl, aminocarbonyloxymethyl, methylaminocarbonyloxymethyl, dimethylaminocarbonyloxymethyl, methylcarbonyl, aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, -NR 5' R 6, -CH 2 -NR 5' R 6, morpholin-4-yl, morpholin-4-ylmethyl, Ar 2, -CH 2 Ar 2, 3,3-difluoroazetidin-1-ylmethyl, pyrrolidin-1-ylmethyl, 1-aminocyclopropyl, 1-methylaminocyclopropyl, and 1-dimethylaminocyclopropyl; R 5 is hydrogen, C 1 -C 3 alkyl, cyanomethyl, -C CH 3, or aminocarbonylmethyl; R 5 is hydrogen, C 1 -C 4 alkyl, cyclopropyl, hydroxyethyl, methoxyethyl, -C CH 3, or -C O(C 1 -C 3) alkyl; R 6 is hydrogen or methyl; R 7 is hydrogen, fluoro, chloro, methyl, hydroxymethyl, or methoxy; Ar 1 is a moiety selected from the group consisting of imidazol-1-yl, imidazol-2-yl, 2-methylimidazol-1-yl, pyrazol-1-yl, 1,2,3-triazol-1-yl; 1,2,3-triazol-2-yl; 1,2,4-triazol-1-yl, isoxazol-3-yl, oxazol-5-yl, and 3-methyl-1,2,4-oxadiazol-5-yl; and Ar 2 is a moiety selected from the group consisting of imidazol-1-yl, imidazol-2-yl, 2-methylimidazol-1-yl, 1-methylimidazol-2-yl, and 1,2,4-triazol-3-yl. A is or R 1 is fluoro or chloro; R 2a and R 2b are each hydrogen or are each fluoro; R 3 is hydrogen, methyl, hydroxymethyl, or (C 1 -C 3) alkoxymethyl; R 4 is selected from the group consisting of fluoro, chloro, cyano, cyanomethyl, (C 1 -C 3) alkyl, cyclopropyl, hydroxymethyl, methoxy, cyclopropylmethoxy, aminocarbonylmethoxy, (C 1 -C 3) alkoxymethyl, cyclopropyloxymethyl, cyclopropylmethoxymethyl, 1-hydroxy-1-methylethyl, aminocarbonyloxymethyl, methylaminocarbonyloxymethyl, dimethylaminocarbonyloxymethyl, aminocarbonyl, aminocarbonylmethyl, -CH 2 -NR 5 R 6, hydroxyimine, methoxyimine, morpholin-4-yl, morpholin-4-ylmethyl, Ar 1, -CH 2 Ar 1, tetrahydrofuran-2-yl, 3-oxomorpholin-4-ylmethyl, 2-oxopyrrolidin-1-ylmethyl, and 2-oxopiperidin-1-ylmethyl; R 4' is selected from the group consisting of fluoro, chloro, cyano, cyanomethyl, (C 1 -C 3) alkyl, cyclopropyl, hydroxymethyl, methoxy, methoxymethyl, aminocarbonyloxymethyl, methylaminocarbonyloxymethyl, dimethylaminocarbonyloxymethyl, methylcarbonyl, aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, -NR 5' R 6, -CH 2 -NR 5' R 6, morpholin-4-yl, morpholin-4-ylmethyl, Ar 2, -CH 2 Ar 2, 3,3-difluoroazetidin-1-ylmethyl, pyrrolidin-1-ylmethyl, 1-aminocyclopropyl, 1-methylaminocyclopropyl, and 1-dimethylaminocyclopropyl; R 5 is hydrogen, C 1 -C 3 alkyl, cyanomethyl, -C CH 3, or aminocarbonylmethyl; R 5 is hydrogen, C 1 -C 4 alkyl, cyclopropyl, hydroxyethyl, methoxyethyl, -C CH 3, or -C O(C 1 -C 3) alkyl; R 6 is hydrogen or methyl; R 7 is hydrogen, fluoro, chloro, methyl, hydroxymethyl, or methoxy; Ar 1 is a moiety selected from the group consisting of imidazol-1-yl, imidazol-2-yl, 2-methylimidazol-1-yl, pyrazol-1-yl, 1,2,3-triazol-1-yl; 1,2,3-triazol-2-yl; 1,2,4-triazol-1-yl, isoxazol-3-yl, oxazol-5-yl, and 3-methyl-1,2,4-oxadiazol-5-yl; and Ar 2 is a moiety selected from the group consisting of imidazol-1-yl, imidazol-2-yl, 2-methylimidazol-1-yl, 1-methylimidazol-2-yl, and 1,2,4-triazol-3-yl.