SAN FRANCISCO (AP) — In case you needed yet another incentive to cram all your travel items into a carry-on, Delta Airlines has just boosted the cost of your first checked bag by 17%.

The increases adds $5 to the previous, and not-exactly-insignificant, $30 fee for domestic flights.

Delta is the third major U.S. carrier to hike bag fees in the past several weeks, following similar increases that American Airlines and United Airlines announced in February, three days apart.

Smaller carriers Alaska Airlines and JetBlue Airways hiked baggage fees earlier this year.

Major U.S. carriers often copy one another’s pricing changes, behavior analysts sometimes refer to as herd instinct.