Yahoo’s search market share continues to grow following the switch by Firefox from Google to Yahoo as the default search engine in their browser.

Many people expected Yahoo’s search market share to start declining after the initial jump, as more users became aware that the default search they were using wasn’t actually Google. But in fact the opposite is true and Yahoo is continuing to grow as Google’s expense.

According to comScore, in January Yahoo gained another 1.2% of search market share in the US. Now this entire announcement didn’t come just from Google. Google lost 1% while the Ask Network lost 0.2% and AOL lost through .1%. Microsoft and their Bing search engine remained the same.

This means that Yahoo now has 13% of the search share, which puts them behind Google with 64.4% and Microsoft with 19.7%

When Firefox made the switch in December, Yahoo gained 1.6% market share, which came directly from Google.

Why is Google continuing to lose market share? The logical assumption is that users are still being switch to yahoo as they update. But some users, despite setting their default search engine to Google find themselves mysteriously switched back to Yahoo as default.

In December’s comScore Yahoo gained 2.6% of the market share, which was the first measurement taken after the Firefox switch.

VentureBeat also notes that Yahoo has been pushing chrome browser visitors to their site to “upgrade” their browser to Firefox followed by Google encouraging their own users to change their default from Yahoo to Google.