A Google GOOG algorithm update taking place on Tuesday could have both big brands and small business owners scrambling to revamp their websites, according to Business Insider.

The search giant will be changing the way results appear based on websites that are deemed mobile-friendly due to the fact that 60% of traffic now comes from mobile devices. For those late to the news, the change could have negative implications starting tomorrow. Sites without text and formatting unsuited for mobile devices will suffer most. In February, Google announced in a blog post:

We will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results. Consequently, users will find it easier to get relevant, high quality search results that are optimized for their devices.

Business Insider reported that the algorithm change is being cast as something sinister: “It has even been nicknamed ‘Mobile-geddon’ because of how ‘apocalyptic’ it could be for millions of websites,” Itai Sadan, CEO of website building company Duda, told Business Insider. Sadan added: “Come April 21, a lot of small businesses are going to be really surprised that the number of visitors to their websites has dropped significantly. This is going to affect millions of sites on the web.”

In January, Google posted fourth quarter earnings of $6.88 a share up from $6.00 a share last year. Revenue rose to $18.1 billion from $16.86 billion.