Handing a win to Amazon.com Inc. and its lawyers at Jenner & Block, a judge on Monday tossed a patent lawsuit alleging that the charger sold with Amazon’s Kindle e-reader is identical to one sold by a small company called VoltStar Technologies Inc.

The ruling by U.S. District Judge John Lee in Chicago dismisses design patent infringement claims that VoltStar brought against Amazon last year. Giving little weight to an expert report proffered by VoltStar, Lee ruled that “a side-by-side comparison would yield the conclusion that the two products create a substantially different visual impression.” (You can compare the two chargers on pages six and seven of Lee’s decision.)

Through its no-frills website, VoltStar sells what calls the “slimmest cell phone charger on the market.” In 2007 it applied for a design patent on the charger. The patent was granted in 2009.

VoltStar sued Amazon in August 2013, alleging that it sold millions of Kindles with an infringing charger. Amazon’s charger is also patented.

“The two chargers look identical,” VoltStar’s lead counsel, Jerold Schneider of Chicago-based Schneider Rothman IP Law Group, said in a press release at the time. “They have a strikingly similar shape, and customers are unlikely to tell them apart.”

Lee took a very different view of the case—and the chargers—writing in Monday’s decision that Amazon’s product plainly has a more oval shape. “An ordinary observer, familiar with the prior art, would be not deceived into thinking that the Amazon design was the same as the VoltStar design,” he wrote.

Amazon is represented by Joshua Segal, Bradford Lyerla and Nicole Berg of Jenner & Block. Segal declined to comment.

Schneider, VoltStar’s lawyer, told us that he thinks Lee misinterpreted precedent he relied on in his decision. Schneider also said his client is weighing an appeal.