There are a lot of reasons Mac users don’t sweat getting infected. One: They’ve got a built-in anti-malware system called XProtect that does a decent job of catching known malware. Two: Macs are not plagued by a high number of attacks. (Most cybercriminals are focused on infecting PCs.) And three: There’s just not a lot of Mac malware out there.

But that’s changing, and fast: Mac malware has increased by 230 percent in the last year alone. Most Mac users don’t know this, and assume their Mac is fine. For those folks we have one word: adware.

Your Mac is infected…with adware

Adware is software that’s designed to display advertisements, usually within a web browser. Most people don’t willingly download programs whose sole purpose is to bombard you with ads, so adware has to sneak its way onto your Mac. It either disguises itself as legitimate or piggybacks on another program in order to be installed.

Once in your system, adware changes the way your browser behaves by injecting ads into web pages, causing pop-up windows or tabs to open, and changing your homepage or search engine—all in the name of funneling advertising dollars away from companies who pay for online ads and into their own accounts.

Your Mac is infected…and not protected

Sounds pretty shady, right? So why doesn’t the Mac anti-malware program catch these guys? Typically, the makers of adware are hiding in plain sight, operating as actual corporations who claim to sell software on the level. They get away with it because their adware is often hidden in the fine print of a long installation agreement that most people skip over. Is it technically legal? Yes. You accepted the terms of the installment so they can spam you all they want. But is it right? So far, Apple hasn’t stepped in to crack down on it. But if you ask us, the answer is an emphatic “no.”

In addition to adware, other potentially unwanted programs, such as so-called “legitimate” keyloggers, scammy “cleaning” apps, and faux antivirus programs that don’t actually detect anything are skirting the Mac protections in place. (Because XProtect doesn’t detect and block adware or potentially unwanted programs—only malware that it has seen before.) So if a new form of malware makes its way onto your computer before Apple has a chance to learn about it and write code to protect against it, then you’re out of luck.

So if you ask us, it’s time to start taking a closer look at your Mac. Is it acting the way your sturdy, reliable Mac has always behaved? Or is it exhibiting classic signs of guilt? If something seems a little off, you just might have a problem. Let’s take a look at the telltale signs that your Mac is infected.

Signs of adware

Advertisements are displayed in places they shouldn’t be, literally popping up everywhere. Your web browser’s homepage has been mysteriously changed without your permission. Web pages that you typically visit are not displaying properly, and when you click on a website link, you get redirected to an entirely different site. In fact, even your search engine has been replaced with a different one. If your web browser, search engine, or websites are acting in funky, unpleasant ways, you’ve likely got yourself an adware infection.

Signs of PUPs

Maybe you downloaded a new program to monitor your family’s behavior online. All of a sudden, new icons are appearing on your desktop for software you don’t remember installing. New toolbars, extensions, or plugins are added to your browser. A pop-up appears telling you your Mac may be infected, and you need to install the latest antivirus immediately to get rid of it. Frightened, you do so, and now your computer has turned the corner from automatically installing apps to slowing to a crawl. What’s going on? These are PUPs, and your Mac’s anti-malware system is not going to get rid of them.

Signs of malware

Mac malware making its way onto your system is, right now, relatively rare. But if it does, you may look out for similar behavior as an infected Windows operating system: your computer’s processing power seems diminished, software programs are sluggish, your browser redirects or is unresponsive, or your ole-reliable starts crashing regularly.

In some cases, you may not be aware of an infection at all. While your computer hums along, info stealers operate quietly in the background, stealing your data for an attack on your bank accounts or identity.

And in the worst case scenario, your Mac can even be infected with ransomware. In March 2016, the first Mac ransomware was spotted, and it was downloaded by thousands of users before Apple had a chance to shut it down. A ransomware attack would be quite obvious to Mac users. Files would be encrypted and cybercriminals would deliver a ransom demand (usually via pop-up) in order to return your data.

Do any of these scenarios sound familiar to you? If so, there are a few steps you can take to remedy the infection. First, back up your files. Next, download a (legitimate) anti-malware program such as Malwarebytes for Mac that’s designed to search and destroy adware, PUPs, and any new forms of malware lurking on the scene. Run a scan and, if there are any nasties hiding away in your pristine Mac OS, it’ll bag, tag, and dump them for you. Then you can finally get your Mac back.