Exhibit (9)(c)

February 15, 2008

State Street Bank and Trust Company
Lafayette Corporate Center
2 Avenue de Lafayette
Boston, MA 02111
Attention: Jeffrey Mihalchik, Vice President

    Re:Gateway Trust (the "Fund")

Ladies and Gentlemen:

Please be advised that the undersigned Fund has been incorporated and
registered as a management investment company under the Investment Company Act
of 1940, as amended.

In accordance with Section 18.6, the Additional Funds provision, of the Master
Custodian Agreement dated as of September 1, 2005 by and among each management
investment company party thereto and State Street Bank and Trust Company (the
"Agreement"), the undersigned Fund hereby requests that your bank act as
Custodian for the Fund under the terms of the Agreement. In addition, in
accordance with Section 18.7, the Additional Portfolios provision, of the
Agreement, the undersigned Fund hereby requests that your bank act as Custodian
with respect to a series of shares established by the Fund and known as the
Gateway Fund, under the terms of the Agreement. In connection with such
requests, the undersigned Fund hereby confirms to you, as of the date hereof,
its representations and warranties set forth in Section 18.4 of the Agreement.

Kindly indicate your acceptance of the foregoing by executing two copies of
this letter agreement, returning one to the Fund and retaining one for your
records.

                                        Sincerely,

                                        GATEWAY TRUST
                                            on behalf of itself and:
                                            GATEWAY FUND

                                        By: /s/ Michael Kardok
                                            ------------------------------------
                                            Name: Michael Kardok
                                            Title: Treasurer Duly Authorized

Agreed and Accepted:

STATE STREET BANK AND TRUSTCOMPANY

By: /s/ Joseph L. Hooley
    ------------------------------------
    Name: Joseph L. Hooley
    Title: Vice Chairman

Effective Date: February 15, 2008