While it might seem like a bad movie plot, websites that aren’t friendly to mobile devices are about to be in for a rude awakening. In late February, one of Google’s top webmasters announced in a blog post that the dominant search engine was about to make a significant change to the way it ranks search results. Beginning on April 21st, its search algorithm would increase the weight it gives when returning search results to what it called “mobile friendliness.” Not only does that mean that mobile-friendly websites would enjoy better results, it also means that sites that don’t meet those standards will face the consequences. Some have already dubbed it “Mobilegeddon.”

The stampede from desktops to the wide variety of shapes and sizes now available as tablets, cell phones and even wearables—think Apple Watch—that has taken place over the past several years is only getting larger. A recent survey by ComScore Networks—a firm that analyzes internet traffic and trends—found that in the final three months of last year, desktop searches in the U.S. decreased, while the searches with smartphones jumped 17 percent. The volume of tablet searches increased 28 percent.

And while many of our clients have made this shift to mobile friendly, they are in the minority. A survey by Didit.com took a look the sites of the largest companies to see if they have adopted a mobile-friendly approach. Didit looked at the home pages of publicly-traded companies on the Standard & Poor’s top 100 list by checking them against Google’s “mobile-friendly test page.” The result—some 25 percent of those home pages failed the test, including the Walt Disney Company, a brand that is typically at the forefront when it comes to leveraging technology for visitors to its theme parks.

The Disney home page looks great on a desktop. But as the screen size gets smaller on table and mobile devices, the Google tool found that the text was too small, the links overlapped each other and the content was often wider than the mobile screen.

We’ve been working with our clients for the past four years to make the move to responsive designs that automatically resize their user interface depending on the size of the display screen. A responsive site takes a standard website and instructs the mobile device on how to display it properly. Responsive websites can handle any resolution with changes in CSS files, which affect how the elements on Web pages are presented. Computers, laptops, smartphones, and tablets will all display the website in the best way possible.

One of the reasons responsive design is so important is the “fat finger” problem—as menus shrink, it becomes nearly impossible to engage the functionality since our fingers are too big. Responsive designs shift the menus from ones that are driven by discreet buttons to larger options that are easier to see and easier to select. Without this type of design, visitors will be frustrated and leave the site in search of one that is user friendly.

This approach insures that the website appropriately presents itself on every size display, from the smallest to the largest. Another approach is to have a separate mobile website. Yet, since new devices in different sizes seem to hit the stores about every 10 minutes, this could be a large problem for websites, and certainly would not be cost-effective.

To put this in perspective, while this is a significant move by Google, it doesn’t mean you have to panic. Some of us have been advising our clients for several years that more and more users are accessing their websites via tablet and mobile devices. Google is simply responding to the shifting trends of how consumers are accessing the web. It will not unduly penalize a website that doesn’t immediately meet its requirements like it did in previous search changes—you can still make the move to a mobile-friendly site and see your rankings adjust accordingly. And if you haven’t been paying attention to the marketplace and to the shifting needs of your audiences, you may have a bigger problem than Mobilegeddon.