A method and system of correcting a packet delay variation, PDV, of express traffic comprising high-priority express packets interspersed at a transmitter (2) by a preemption mechanism with a best-effort traffic comprising low-priority best-effort packets, wherein the method comprises the steps of: calculating (S1) at the transmitter (2) a preemption delay value, PRDV, which indicates a preemption delay, PD, introduced by the preemption mechanism; writing (S2) the calculated preemption delay value, PRDV, into a delay header field of a header of a high-priority express packet transmitted by said transmitter (2) via a signal line (4) to a receiver (3); extracting (S3) the preemption delay value, PRDV, from the delay header field of the header of the high-priority express packet received by the receiver (3) via the signal line (4) from the transmitter (2); calculating (S4) at the receiver (3) a variation compensation delay, VCD, value by subtracting the extracted preemption delay value, PRDV, from a predetermined worst-case preemption delay value, PRDVworst; and applying (S5) at the receiver an additional delay to the high-priority express packet according to the calculated variation compensation delay, VCD, value to compensate the preemption delay, PD, introduced by the preemption mechanism at the transmitter (2).