The invention relates to antibacterial compounds of formula I wherein X is N or CH; R1 is H or halogen; R2 is alkynyloxy or the group M; R3 is H or halogen; M is one of the groups MA and MB represented below wherein A is a bond, CH2CH2, CH═CH or C≡C; R1A is H or halogen; R2A is H, alkoxy or halogen; R3A is H, alkoxy, hydroxyalkoxy, alkoxyalkoxy, thioalkoxy, trifluoromethoxy, amino, hydroxyalkyl, 2-hydroxyacetamido, 1-aminocyclopropyl, 1-hydroxymethyl-cycloprop-1-yl, 1-((phosphonooxy)methyl)cyclopropyl, 1-(((dimethylglycyl)oxy)methyl)cyclopropyl, trans-2-hydroxymethyl-cycloprop-1-yl, 1,2-dihydroxyethyl, 3-hydroxyoxetan-3-yl, 3-(hydroxyalkyl)oxetan-3-yl, 3-aminooxetan-3-yl, 3-hydroxythietan-3-yl, morpholin-4-ylalkoxy, morpholin-4-yl-alkyl, oxazol-2-yl or [1,2,3]triazol-2-yl; and R1B is hydroxyalkyl, dihydroxyalkyl, aminoalkyl, 1-hydroxymethyl-cycloprop-1-yl, 1-aminomethyl-cycloprop-1-yl, trans-2-hydroxymethyl-cycloprop-1-yl, 3-hydroxyoxetan-3-yl, 3-hydroxythietan-3-yl, 1-(2-hydroxyacetyl)azetidin-3-yl, 1-(2-aminoacetyl)azetidin-3-yl, 1-glycylazetidin-3-yl, 1-(2-amino-2-methylpropanoyl)azetidin-3-yl, 3-(2-aminoacetamido)cyclopentyl, trans-(cis-3,4-dihydroxy)-cyclopent-1-yl or 3-hydroxymethylbicyclo[1,1,1]pentan-1-yl; and salts thereof.