Composition, comprising c) at least one azole and d) at least one phenol of the formula (I) or a salt thereof in which R1, R2, R3, R4 and R5 each independently of one another represent hydrogen, optionally substituted C1-C20-alkyl, C2-C20-alkenyl, C7-C18-alkylaryl or C3-C20-cycloalkyl, with the proviso that at least one of the radicals R1-R5 is not hydrogen and with the proviso that, if the radicals R1-R5 exclusively represent optionally substituted C1-C20-alkyl or optionally hydrogen at least one of the radicals R1-R5 represents a C1-C2-alkyl radical substituted by a phenyl radical, where the phenyl radical is optionally substituted by hydroxyl and/or C1-C4-alkyl and the compound of the formula (I) carries at least one methyl group.