AWS CEO Adam Selipsky is trying to convince customers that cloud computing can save them money, but many are unconvinced.

Amid an uncertain economy, companies are looking to cut costs everywhere. Selipsky is touting cloud computing as a way for companies to save money, according to Business Insider.

“When it comes to the cloud, many of our customers know they should be leaning in precisely because of economic uncertainty, not despite it. The cloud is more cost-effective,” Selipsky said, adding: “If you are looking to tighten your belt, the cloud is the place to do it.”

Despite the CEO’s confidence, many customers are not convinced that cloud costs can be kept under control. Pay-as-you-go cloud computing sounds good, but costs can quickly escalate as companies begin to scale up.

“Especially in the past month and a half, the volume of inbound calls we’re getting from startups saying, ‘We need to cut our costs dramatically’” has increased, Ken Cheney, the chief revenue officer at Ternary, told Insider. “It’s the macro conditions, right? Suddenly spending money like a drunken sailor doesn’t make sense.”

This isn’t the first time cost has come up as a concern with cloud computing. In August, Anodot’s State of Cloud Cost Report found that 50% of IT executives said it was proving difficult to control cloud costs.

Unless costs are managed carefully, it’s quite easy to lose track of what’s being used—especially for organizations with large development teams that move quickly and tend to try new things. Misconfigurations, over-provisioning, and forgotten resources that have been provisioned but abandoned are the bane of cost management for DevOps teams. Unfortunately, for many organizations, the surprise costs only show up when the monthly invoice arrives.

If companies continue to struggle with cloud computing costs, AWS and others may have their work cut out convincing customers to continue spending money.