Exhibit 23(a)

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of our report dated February 25, 2014 relating to the financial statements, financial statement schedule and the effectiveness of internal control over financial reporting, which appears in United States Steel Corporation’s Annual Report on Form 10-K for the year ended December 31, 2013.

/s/ PricewaterhouseCoopers LLP        

PricewaterhouseCoopers LLP

Pittsburgh, Pennsylvania

May 22, 2014