The invention relates to a process for improving the color fastness of a dyed keratin fiber comprising applying to said fiber (a) at least one dye composition containing, in a medium suitable for dyeing, at least one oxidation base selected from bis(phenyl)alkylenediamines, para-aminophenols, ortho-aminophenols, heterocyclic bases and para-phenylenediamines of formula (I), and the addition salts of these compounds with an acid: ##STR1## in which: R.sub.1 represents a hydrogen atom or a C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 monohydroxyalkyl, C.sub.2 -C.sub.4 polyhydroxyalkyl, phenyl or 4'-aminophenyl radical, R.sub.2 represents a hydrogen atom or a C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 monohydroxyalkyl or C.sub.2 -C.sub.4 polyhydroxyalkyl radical, R.sub.3 represents a hydrogen atom, a halogen atom, or a C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 monohydroxyalkyl or C.sub.1 -C.sub.4 hydroxyalkoxy radical, and R.sub.4 represents a hydrogen atom or a C.sub.1 -C.sub.4 alkyl radical, and (b) developing the color at acidic, neutral or alkaline pH using an oxidizing agent, wherein said oxidizing agent is added to said dye composition at the time of use or is present in an oxidizing composition applied simultaneously or sequentially in a separate manner from said dye composition, wherein said dye composition, said oxidizing composition, or both, contain at least one ceramide compound.