Amazon is vying to become the largest apparel seller in the US, where it already trails only Walmart. But even those who buy clothes on the site say Amazon isn’t a destination for fashion.

The e-commerce giant’s success selling clothing is being fueled by millennials with Amazon Prime. Members of the loyalty program are twice as likely as other Amazon shoppers to buy clothes from Amazon, according to research from Morgan Stanley. Shoppers aged 18 to 34, meanwhile, are more likely to buy clothes from Amazon than those in any other age bracket.

A March 2018 survey of 1,103 US adults by Morgan Stanley found that shoppers are turning to Amazon.com for casual tops (68% of respondents purchased), casual bottoms (38%), shoes (48%), and athletic wear (34%). A good number of them are also using Amazon to buy accessories (26%), dresses (23%), and underwear (24%).

Basics are Amazon’s forte. What it’s not good at? Selling clothes that customers find fashionable. In the same survey, Morgan Stanley asked respondents for the top reason they purchased clothes on Amazon. The most popular reason, cited by 28% of respondents, was “Amazon is an easy/convenient shopping experience.” Other common reasons were being a Prime member (free two-day shipping is still a good sell), Amazon’s low prices, and Amazon’s wide selection. Only 6% chose “Amazon offers fashionable clothing and the brands I like” as the top reason for buying clothes from there, down from an already dismal 8% in 2017.

Morgan Stanley also flipped the question, asking people for the main reason they decided not to purchase clothes from Amazon. The most common response to that question came from the 37% of people who said they preferred to try their clothes on in-store before buying. The next most common reason was fashion: 20% of respondents said they didn’t “consider Amazon to be a destination for fashionable clothing,” more than triple the share who said that in 2017.

Despite conquering most of retail and selling a lot of clothes, Amazon has consistently struggled to sell fashion. That’s partly because luxury designers, who rely upon prestige and exclusivity, aren’t inclined to make their wares widely available on the internet, and partly because the people who shop on Amazon, as Morgan Stanley found, are looking for affordable, quickly delivered basics more than high-end designs. At least for now, that makes fashion a small corner of retail that can consider itself somewhat resistant to Amazon.