Halliburton has joined rival Schlumberger in curbing activity in Venezuela due to lack of payment during the oil industry’s worst financial crisis.

“During the first quarter of 2016, we made the decision to begin curtailing activity in Venezuela,” Halliburton, the world’s second-largest oil services provider, said Friday in a filing with the U.S. Securities and Exchange Commission.

“We have experienced delays in collecting payment on our receivables from our primary customer in Venezuela. These receivables are not disputed, and we have not historically had material write-offs relating to this customer,” the company said.

Halliburton’s receivables in Venezuela rose 7.4% in the first quarter to $756 million compared to the end of 2015, representing more than 10% of its total receivables, the Houston-based company said. It’s the only country or customer that represents more than 10% of receivables, it said. Halliburton did not name the customer in the filing.

Halliburton’s shares are down 1% to $39.54 at 1:45 p.m. and up 16% since the start of the year.

Schlumberger said last month it was reducing activity in the Latin American country because it had failed to collect enough payments from national oil company Petroleos de Venezuela SA.

Venezuela, which holds the biggest oil reserves of any country, has been battered by the collapse of prices as most of the government’s revenue comes from petrodollars.

After Schlumberger’s activity-cutback announcement, the Venezuelan oil giant denied it was struggling to pay its bills. In a statement that same day, PDVSA said Schlumberger was not reducing activity and labeled the reports of cutbacks “manipulation” by the media. It said at the time it would continue to make payments in “various forms” to the service provider.

A spokeswoman for Halliburton did not immediately reply to an emailed request for comment on the customer. A spokeswoman for PDVSA did not immediately respond to an email and phone call.