In this paper we consider two particular Canadian defined benefit pension plans to illustrate the importance of adequate mortality forecasting on actuarial liabilities. An employer who sets up an employee defined benefit pension plan promises to periodically pay a certain sum to the participant until death. Both the employee and the employer finance these periodical payments during the beneficiary's career. Any shortcoming of funds in the future is, however, the employer's responsibility. It is therefore essential for the employer to be able to predict with a high degree of confidence the total amount that will be required to cover its obligations to the future retiree. If increases in life expectancy were predictable and taken into consideration when establishing retirement funds, assessing future liabilities would be riskless in that respect. Unfortunately, future survival rates are uncertain. On that account, pensioners may outlive their life expectancies and expose pension funds to longevity risk. We present different tools to hedge this risk and the potential cost for two Canadian public pension plans.