<PAGE>

EXHIBIT 10.8

                          AMENDMENT TO EMPLOYMENT/STOCK
                              REPURCHASE AGREEMENT


         THIS IS AN AMENDMENT (the "Amendment") to that certain Employment/Stock
Repurchase Agreement dated October 13, 1999 (the "Agreement") between MPOWER
HOLDING CORPORATION, a Delaware corporation which is successor in interest to
MPOWER COMMUNICATIONS CORP., a Nevada corporation formerly known as MGC
COMMUNICATIONS, INC. (the "Company") and ROLLA P. HUFF ("Executive").

         The Company and Executive, for and in consideration of the promises,
terms and conditions contained herein, do hereby agree to make the following
changes to the Agreement, which modifications shall take precedence over any
conflicting terms contained in the Agreement.

         1. Unless Executive's employment with Company is terminated for "Cause"
(as defined in Item 11A of the Agreement) prior to October 13, 2002, the Company
agrees that the cash signing bonus paid to Executive pursuant to Item 4C of the
Agreement shall become immediately fully vested such that Executive shall not be
required to repay the cash signing bonus or any portion thereof under any other
circumstances whatsoever. In the event Executive's employment with Company is
terminated for Cause prior to October 13, 2002, then Executive shall be required
to repay to Company the $1,000,000 cash signing bonus within thirty (30) days of
Executive's termination of employment.

         2. The Company and Executive hereby agree to rescind Item 9 of the
Agreement in its entirety. In that regard, Executive agrees to promptly deliver
to the Company the Note Shares (as defined in the Agreement) for cancellation,
along with a stock power for such purpose as shall be reasonably requested by
the Company. The Company shall deliver to Executive for cancellation the
original non-recourse Note (as defined in the Agreement). Company and Executive
acknowledge that as a result of a stock split implemented by the Company in
August 2000, the Note Shares now consist of 225,000 shares of Common Stock of
the Company.

         3. Executive hereby agrees to indemnify the Company and hold it
harmless from any cost, expense or loss the Company may incur as a result of any
claim or action brought by any person claiming an interest in the Note Shares.

         4. The Company hereby agrees to indemnify Executive and hold him
harmless from any cost, expense or loss Executive may incur as a result of any
claim or action brought by any person claiming an interest in the non-recourse
Note.


<PAGE>

         5. Executive and the Company agree to execute such additional documents
and do such further acts and deeds as may be necessary or desirable to
effectuate the purposes hereof and for the perfection of the rights and
interests of the other party hereto expressed herein.

         6. The waiver by either party of any provision of this Amendment shall
not operate as, or be construed to be, a waiver of any subsequent breach hereof.

         7. This Amendment shall inure to the benefit of and be binding upon the
parties hereto and their respective successors and assigns.

         8. Each party has had the opportunity to be represented by counsel of
its choice in negotiating this Amendment. This Amendment shall therefore be
deemed to have been negotiated and prepared at the joint request and direction
of the parties, at arm's length, with the advice and participation of counsel,
and shall be interpreted in accordance with its terms and without favor to any
party.


         IN WITNESS WHEREOF, the parties hereto have executed this Amendment on
August 1, 2001.




COMPANY:                                          EXECUTIVE:
Mpower Holding Corporation


By:
   -------------------------                      ------------------------------
      Russell I Zuckerman                                 Rolla P. Huff


Its: Sr. Vice President and General Counsel



                                       2