Packing a carry-on sounds simple enough, but it’s surprisingly easy to waste valuable space or accidentally bring items that could cause delays at security. While some of these mistakes are obvious, others catch travelers off guard every day and can leave you frustrated before your trip even begins.

If you’re trying to travel lighter, get through security faster, and avoid unnecessary headaches, here are nine things to leave out of your carry-on bag.

Flammable Products

Many travelers don’t realize that certain aerosols, fuels, and other flammable items are prohibited in carry-on luggage. Even if the container seems small, it could be confiscated at security if it doesn’t meet TSA guidelines.

Firearms, Knives, and Other Weapons

Weapons of any kind are among the most common reasons travelers are stopped at airport security. Firearms, ammunition, pocketknives, multi-tools, stun guns, pepper spray, and other self-defense items are generally prohibited in carry-on bags, and many travelers don’t realize they’re carrying them until TSA points them out.

If you plan to travel with a firearm, it must typically be unloaded, secured in a locked hard-sided case, packed in checked baggage, and declared to the airline. Before heading to the airport, double-check every pocket, pouch, and compartment of your bags; many confiscated knives and tools are items that travelers simply forgot were there.

Oversized Bottles of Liquids

Bringing your favorite shampoo, sunscreen, or a full-size bottle of liquor can quickly cause problems at security. Most liquids in carry-on bags must follow the TSA’s 3.4-ounce rule, regardless of how much product remains in the container.

Bulky Winter Jackets

Stuffing a heavy coat into your carry-on can consume a surprising amount of space that could be used for more important items. If you’re traveling with a bulky jacket, it’s usually easier to wear it through the airport and remove it once you’re seated.

Full-Size Travel Pillows

Traditional neck pillows can be comfortable, but they’re also notorious space hogs. Inflatable travel pillows provide similar support while taking up only a fraction of the room in your bag.

Hair Dryers and Bulky Styling Tools

Hair dryers, curling irons, and other styling tools can take up a significant amount of space, especially on shorter trips. Since many hotels and vacation rentals already provide hair dryers, it may be worth checking your accommodations before packing one.

Gifts That Need Wrapping

Wrapped gifts often trigger additional screening because security agents can’t easily inspect what’s inside. Bringing gifts unwrapped and wrapping them after you arrive can save time and prevent awkward delays at the checkpoint.

Large Food Containers

Travelers are often surprised to learn that foods like peanut butter, yogurt, dips, gravy, and soft cheeses are treated as liquids or gels by TSA. If the container exceeds the allowed limit, it may end up in the trash before you ever reach your gate.