Third Amendment to Marketing Agent Agreement among ALPS Distributors, Inc., United States Commodity Funds LLC, and United States Oil Fund, LP (February 19, 2013)

Exhibit 10.5

THIRD AMENDMENT

DATED AS OF FEBRUARY 19, 2013

TO THE MARKETING AGENT AGREEMENT

DATED AS OF MARCH 13, 2006, AS AMENDED MARCH 24, 2008 AND

JULY 30, 2012

AMENDMENT AGREEMENT (the “Amendment”) dated as of February 19, 2013 between ALPS DISTRIBUTORS, INC. (“ALPS”), UNITED STATES COMMODITY FUNDS LLC, formerly Victoria Bay Asset Management, LLC (“USCF”), and UNITED STATES OIL FUND, LP (“USOF”).

WITNESSETH

The parties have previously entered into that certain Marketing Agent Agreement dated as of March 13, 2006, as amended on March 24, 2008 and July 30, 2012 (the “Agreement”). The parties have agreed to amend the Agreement in accordance with the terms of this Amendment.

NOW, THEREFORE, in consideration of the mutual agreements herein contained, ALPS, USCF and USOF hereby acknowledge and agree as follows:

1. Amendment to the Agreement. Upon execution of this Amendment by ALPS, USCF and USOF, the Agreement shall be hereby amended as follows:

(a) Section 4.3 of the Agreement, “Marketing Agent Fee” shall be amended by adding the following:

In no event will the Marketing Agent Fee exceed 10% of the gross proceeds of the Fund’s offering.

IN WITNESS WHEREOF, the parties have caused this Amendment to be executed by their respective officers or authorized representatives as of the day and year first above written.

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