Ben Franklin may have known about electricity, politics, bifocals and one or two other things, but one of his more overlooked gifts to posterity is this immortal observation: “Guests, like fish, begin to smell after three days.” What he didn’t say is this: If they’re your roommate’s guests, rather than your own, the smell can set in a whole lot faster. Strangers in close confines can  make for uncomfortable  situations. You can’t eradicate this awkwardness altogether, of course, but there are ways to make it easier for everyone. Pleasant, even. If you’re inviting a guest over, especially someone who’s staying more than one night, here are a few basic things to bear in mind so you can keep the peace with your roommate.

First and foremost, practice good communication. This is really, really important. Really. Unless your guest is going to enter and exit through your bedroom window, he or she will almost certainly be using the shared spaces of your apartment–the key word there being “shared.” It’s your roommate’s place just as much yours, so it’s absolutely key that you give the proper advance warning that there will be another person around. Put yourself in your roommate’s shoes: it’s jarring enough to get home one evening and find a stranger coming out of your bathroom, or to see your roommate snuggling on the couch with someone you’ve never seen before, right? Well, it’s even more disconcerting, even more of an affront to basic expectations of personal space and privacy, to wake up in the morning and stumble to the kitchen in your underwear, only to encounter an unexpected stranger. So chat with your roommate before your guest arrives, give at least a one-sentence description of who the guest is–a cousin, a couch-surfer, a college friend–and be sure to ask if your roommate has any questions or concerns. As always, it’s just good form to keep your roommate in the loop.

When you’re having this discussion, keep the tone light and friendly. Roommate relations can be tricky, and adding another person into the mix, even for one night or a few hours, can make things even more complicated. So keep it a casual, friendly conversation–you’re a diplomat here, not a dictator. But do make sure everyone has an understanding of how to interact and what to expect.

Make it clear how long the guest will be around. Will it be a day? A weekend? Make sure your roommate is okay with that, and offer reassurance that your guest will be respectful and discreet. Also realize that even the most polite guest can seem like a major intrusion if he or she is around for more than a few days–or if, for example, your roommate is in the middle of finals or just starting a new job or dealing with any of those big-deal, stressful life situations for which the space, privacy, and predictability of home offer a much-needed balm.

Establish some basic rules and expectations for both your roommate and your guest. If either one has a habit of wandering around the house in the nude, or cooking elaborate meals and neglecting to clean up the kitchen, now would be a great time to ask that this sort of thing be halted, at least temporarily. Do either of them have more low-key but still notable quirks, habits, or needs that need to be explained? Are there areas of the apartment, or things like specific food in the refrigerator, that your guest should understand are off-limits? Make sure everyone understands these basic  things.

DON’T get too close and cuddly outside the bedroom, if your guest is a boyfriend, girlfriend, or any sort of romantic interest. Don’t make your roommate feel uncomfortable, and know where that boundary lies. Some people might not particularly care if you kiss in front of them; others will start to squirm at the slightest hint of verbal flirting. Just understand–and respect–the specific boundaries of comfort, and if you’re at all uncertain, err on the side of discretion. (Besides, you probably don’t want to flirt with someone else staring uncomfortably, do you?)

DO socialize together! If you’re watching a movie or playing a game in the living room, invite your roommate to join you. With any luck, you’ll all become friends.