Have you noticed some regular household items you want to buy on Walmart.com are out of stock? There may be a good reason for that.

Walmart changed its e-commerce systems to avoid orders deemed too expensive to ship and started telling customers those items are "out of stock," according to The Wall Street Journal. If the item is stored in a warehouse that's too far from a shopper, the company reportedly won't sell and ship it.

Walmart didn't immediately respond to a request for confirmation and comment on the report. But the Journal says the company introduced the system earlier this month and some suppliers weren't warned of this change in advance. Suppliers reportedly have to stock their products at more Walmart warehouses nationwide to keep the items "in stock" on the retailing website, which has to compete fiercely with e-commerce giant Amazon. 

The change was a test run aimed to deliver more items using ground shipping, which is cheaper than air shipping, the Journal said.