EXHIBIT NO. 99.(a) 30

MFS SERIES TRUST X

CERTIFICATION OF AMENDMENT

TO THE DECLARATION OF TRUST

TERMINATION OF CLASS

Pursuant to Section 9.2(b) of the Amended and Restated Declaration of Trust, dated as of December 16, 2004, as amended (the “Declaration”), of MFS Series Trust X (the “Trust”), the undersigned, constituting a majority of the Trustees of the Trust, do hereby certify that Class 529A, 529B, and 529C Shares of MFS International Diversification Fund, a series of the Trust, have been terminated.

IN WITNESS WHEREOF, a majority of the Trustees of the Trust have executed this amendment, in one or more counterparts, all constituting a single instrument, as an instrument under seal in The Commonwealth of Massachusetts, as of July 29, 2016 and further certify, as provided by the provisions of Section 9.3(c) of the Declaration, that this amendment was duly adopted by the undersigned in accordance with Section 9.3(a) of the Declaration.

STEVEN E. BULLER	JOHN P. KAVANAUGH
Steven E. Buller	John P. Kavanaugh
c/o MFS Investment Management	c/o MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
ROBERT E. BUTLER	ROBERT J. MANNING
Robert E. Butler	Robert J. Manning
c/o MFS Investment Management	MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
MAUREEN R. GOLDFARB	MARYANNE L. ROEPKE
Maureen R. Goldfarb	Maryanne L. Roepke
c/o MFS Investment Management	c/o MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
DAVID H. GUNNING	ROBIN A. STELMACH
David H. Gunning	Robin A. Stelmach
c/o MFS Investment Management	MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
WILLIAM R. GUTOW	LAURIE J. THOMSEN
William R. Gutow	Laurie J. Thomsen
c/o MFS Investment Management	c/o MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199
MICHAEL HEGARTY	ROBERT W. UEK
Michael Hegarty	Robert W. Uek
c/o MFS Investment Management	c/o MFS Investment Management
111 Huntington Avenue	111 Huntington Avenue
Boston, MA 02199	Boston, MA 02199