Copolycarbonate composition comprising: A) 5% to 99% by weight of a copolycarbonate containing one or more monomer units of the formula in which R 1 is hydrogen or C 1 -C 4 -alkyl, R 2 is C 1 -C 4 -alkyl, and n is 0, 1, 2 or 3, B) 95% to 1% by weight of a (co)polycarbonate containing one or more monomer units of the general formula: in which R 3 is H, linear or branched C 1 -C 10 alkyl, and R 4 is linear or branched C 1 -C 10 alkyl, and where component B) does not have any monomer units of the formula; characterized in that component B contains at least one cyclic oligomer of the general formula in an amount of 0.3% to 0.75% by weight, based on the weight of component B, where n is an integer from 2 to 6, and Z is a radical of the formula (Ia) in which R 5 and R 6 are independently H or C 1 -C 8 -alkyl, and X is a single bond, C 1 - to C 6 -alkylene, C 2 -to C 5 -alkylidene or C 5 - to C 6 -cycloalkylidene, which may be substituted by C 1 - to C 6 -alkyl, and component B contains one or more linear oligomer(s) of the general formulae,,, and/or in an amount of 0.40% by weight to 1.40% by weight, based on the weight of component B, where k, 1, m, o and p may each be independently an integer from 1 to 6 and Z is the radical of the formula (Ia) already defined; and where the total amount of the structures and to is determined by dissolving component B) in methylene chloride, precipitating with acetone, concentrating the filtrate to dryness, dissolving the dry residue in tetrahydrofuran, and subsequent quantitative HPLC with UV detection. A) 5% to 99% by weight of a copolycarbonate containing one or more monomer units of the formula in which R 1 is hydrogen or C 1 -C 4 -alkyl, R 2 is C 1 -C 4 -alkyl, and n is 0, 1, 2 or 3, R 1 is hydrogen or C 1 -C 4 -alkyl, R 2 is C 1 -C 4 -alkyl, and n is 0, 1, 2 or 3, B) 95% to 1% by weight of a (co)polycarbonate containing one or more monomer units of the general formula: in which R 3 is H, linear or branched C 1 -C 10 alkyl, and R 4 is linear or branched C 1 -C 10 alkyl, and where component B) does not have any monomer units of the formula; characterized in that component B contains at least one cyclic oligomer of the general formula in an amount of 0.3% to 0.75% by weight, based on the weight of component B, where n is an integer from 2 to 6, and Z is a radical of the formula (Ia) in which R 5 and R 6 are independently H or C 1 -C 8 -alkyl, and X is a single bond, C 1 - to C 6 -alkylene, C 2 -to C 5 -alkylidene or C 5 - to C 6 -cycloalkylidene, which may be substituted by C 1 - to C 6 -alkyl, and component B contains one or more linear oligomer(s) of the general formulae,,, and/or in an amount of 0.40% by weight to 1.40% by weight, based on the weight of component B, where k, 1, m, o and p may each be independently an integer from 1 to 6 and Z is the radical of the formula (Ia) already defined; and where the total amount of the structures and to is determined by dissolving component B) in methylene chloride, precipitating with acetone, concentrating the filtrate to dryness, dissolving the dry residue in tetrahydrofuran, and subsequent quantitative HPLC with UV detection. R 3 is H, linear or branched C 1 -C 10 alkyl, and R 4 is linear or branched C 1 -C 10 alkyl, and where component B) does not have any monomer units of the formula; characterized in that component B contains at least one cyclic oligomer of the general formula in an amount of 0.3% to 0.75% by weight, based on the weight of component B, where n is an integer from 2 to 6, and Z is a radical of the formula (Ia) in which R 5 and R 6 are independently H or C 1 -C 8 -alkyl, and X is a single bond, C 1 - to C 6 -alkylene, C 2 -to C 5 -alkylidene or C 5 - to C 6 -cycloalkylidene, which may be substituted by C 1 - to C 6 -alkyl, and component B contains one or more linear oligomer(s) of the general formulae,,, and/or in an amount of 0.40% by weight to 1.40% by weight, based on the weight of component B, where k, 1, m, o and p may each be independently an integer from 1 to 6 and Z is the radical of the formula (Ia) already defined; n is an integer from 2 to 6, and Z is a radical of the formula (Ia) in which R 5 and R 6 are independently H or C 1 -C 8 -alkyl, and X is a single bond, C 1 - to C 6 -alkylene, C 2 -to C 5 -alkylidene or C 5 - to C 6 -cycloalkylidene, which may be substituted by C 1 - to C 6 -alkyl, and component B contains one or more linear oligomer(s) of the general formulae,,, and/or in an amount of 0.40% by weight to 1.40% by weight, based on the weight of component B, where k, 1, m, o and p may each be independently an integer from 1 to 6 and Z is the radical of the formula (Ia) already defined; R 5 and R 6 are independently H or C 1 -C 8 -alkyl, and X is a single bond, C 1 - to C 6 -alkylene, C 2 -to C 5 -alkylidene or C 5 - to C 6 -cycloalkylidene, which may be substituted by C 1 - to C 6 -alkyl, and where the total amount of the structures and to is determined by dissolving component B) in methylene chloride, precipitating with acetone, concentrating the filtrate to dryness, dissolving the dry residue in tetrahydrofuran, and subsequent quantitative HPLC with UV detection.