A colorant for keratin fibers, in particular for human hair, containing, based on its weight, a) at least one compound selected from the group of oxidation dye precursors, substantive dyes and mixtures thereof, b) 0.1 to 5 wt.%, in each case converted to the undissociated dicarboxylic acid and based on the weight of the colorant, dicarboxylic acid(s) having 2 to 10 carbon atoms, selected from malic acid, D-tartaric acid, L-tartaric acid, meso-tartaric acid, racemic acid, alpha-ketoglutaric acid, beta-ketoglutaric acid and oxaloacetic acid, and/or salt(s) of these acid(s), c) 20 to 95 wt.% water, and d) less than 0.1 wt.% peroxide compound(s), characterized in that 0.05 to 5 wt.%, preferably 0.1 to 4.5 wt.%, more preferably 0.15 to 4 wt.%, even more preferably 0.2 to 3.5 wt.% and in particular 0.25 to 3 wt.% oxidation dye precursors are contained, further characterized in that the at least one dicarboxylic acid having 2 to 10 carbon atoms is selected from malic acid, further characterized in that said colorant also contains mixtures of arginine and lysine in a total amount of 0.05 to 3 wt.%, preferably 0.1 to 2 wt.%, particularly preferably 0.2 to 1.2 wt.%, in each case converted to the undissociated amino acid and based on the weight of the colorant, at least one amino acid from the group arginine, lysine, histidine, asparagine, glutamine, cysteine, methionine, tryptophan and mixtures thereof being contained in a total amount of 0.05 to 3 wt.%, preferably 0.1 to 2 wt.%, particularly preferably 0.2 to 1.2 wt.%, in each case converted to the undissociated acid and based on the weight of the colorant, and characterized by a pH in the range of 8.5 to 11.0, preferably 10 to 10.5, in each case measured at 20 °C. a) at least one compound selected from the group of oxidation dye precursors, substantive dyes and mixtures thereof, b) 0.1 to 5 wt.%, in each case converted to the undissociated dicarboxylic acid and based on the weight of the colorant, dicarboxylic acid(s) having 2 to 10 carbon atoms, selected from malic acid, D-tartaric acid, L-tartaric acid, meso-tartaric acid, racemic acid, alpha-ketoglutaric acid, beta-ketoglutaric acid and oxaloacetic acid, and/or salt(s) of these acid(s), c) 20 to 95 wt.% water, and d) less than 0.1 wt.% peroxide compound(s), characterized in that 0.05 to 5 wt.%, preferably 0.1 to 4.5 wt.%, more preferably 0.15 to 4 wt.%, even more preferably 0.2 to 3.5 wt.% and in particular 0.25 to 3 wt.% oxidation dye precursors are contained, further characterized in that the at least one dicarboxylic acid having 2 to 10 carbon atoms is selected from malic acid, further characterized in that said colorant also contains mixtures of arginine and lysine in a total amount of 0.05 to 3 wt.%, preferably 0.1 to 2 wt.%, particularly preferably 0.2 to 1.2 wt.%, in each case converted to the undissociated amino acid and based on the weight of the colorant, at least one amino acid from the group arginine, lysine, histidine, asparagine, glutamine, cysteine, methionine, tryptophan and mixtures thereof being contained in a total amount of 0.05 to 3 wt.%, preferably 0.1 to 2 wt.%, particularly preferably 0.2 to 1.2 wt.%, in each case converted to the undissociated acid and based on the weight of the colorant, and characterized by a pH in the range of 8.5 to 11.0, preferably 10 to 10.5, in each case measured at 20 °C. characterized in that 0.05 to 5 wt.%, preferably 0.1 to 4.5 wt.%, more preferably 0.15 to 4 wt.%, even more preferably 0.2 to 3.5 wt.% and in particular 0.25 to 3 wt.% oxidation dye precursors are contained, further characterized in that the at least one dicarboxylic acid having 2 to 10 carbon atoms is selected from malic acid, further characterized in that said colorant also contains mixtures of arginine and lysine in a total amount of 0.05 to 3 wt.%, preferably 0.1 to 2 wt.%, particularly preferably 0.2 to 1.2 wt.%, in each case converted to the undissociated amino acid and based on the weight of the colorant, at least one amino acid from the group arginine, lysine, histidine, asparagine, glutamine, cysteine, methionine, tryptophan and mixtures thereof being contained in a total amount of 0.05 to 3 wt.%, preferably 0.1 to 2 wt.%, particularly preferably 0.2 to 1.2 wt.%, in each case converted to the undissociated acid and based on the weight of the colorant, and characterized by a pH in the range of 8.5 to 11.0, preferably 10 to 10.5, in each case measured at 20 °C.