Good luck getting a big raise if you’re in a union right now. That’s the unspoken message of a July 29 report from the federal Bureau of Labor Statistics. It showed that nonunion workers’ nominal pay in June was up 5.8% year over year, compared with only 3.8% for union workers’. The gap has been widening for a year.

Why? Inflation. This divergence makes sense when you think of how union contracts operate. Unions negotiate long-term collective-bargaining agreements between workers and employers, with a typical contract lasting three to five years. That locks in the union’s gains but leaves it with little bargaining power or flexibility when something sudden or severe, like the current inflation, hits. So unless the contract is about to expire, union members are trapped when they need the freedom to negotiate better raises much faster.