AbstractGiven that not all suggestions can be implemented, understanding how supervisors can turn down employee voiced suggestions while not discouraging employees voicing in the future is critical for theoretical and practical reasons. Supervisors may use humour when not endorsing employees' suggestions as they attempt to ease tension by injecting something lighthearted, but doing so, we argue, is not uniformly beneficial. Hence, we conducted a preregistered study that tests how supervisors' use of humour when turning down an employee's voiced suggestion affects voice resilience. Utilizing signaling theory, we theorize supervisors' use of humour when turning down voice strengthens voice safety but weakens voice impact perceptions. Indirectly, humour therefore may constitute a mixed blessing for voice resilience (voice behaviour after voice non‐endorsement). Additionally, we hypothesized that the positive link between humour and voice safety and the negative link between humour and voice impact are moderated by supervisor–employee relationship quality (leader–member exchange (LMX)). We tested these predictions in a time‐lagged study of 343 employees whose voice was recently turned down. Humour indeed increased voice resilience via voice safety; against expectations, humour positively related to voice impact (via it, resilience). LMX is significantly moderated. However, unexpectedly, humour helped voice safety, impact and the resilience of low LMX employees.