Exhibit 10.1.2

AMENDMENT NO. 1

TO

REGISTRATION RIGHTS AGREEMENT

AMENDMENT NO. 1 TO REGISTRATION RIGHTS AGREEMENT (this “Amendment”), dated as of
May 13, 2008, made among PAETEC Holding Corp., a Delaware corporation (the
“Company”), and each stockholder of the Company listed on the signature pages
hereof under the heading “Stockholders” (the “Stockholders”).

WITNESSETH:

WHEREAS, pursuant to the Agreement and Plan of Merger, dated as of September 17,
2007, as amended (the “Merger Agreement”), among the Company, McLeodUSA
Incorporated, a Delaware corporation, and PS Acquisition Corp., a Delaware
corporation, the Stockholders received shares of the common stock, par value
$0.01 per share, of the Company (the “Common Stock”);

WHEREAS, pursuant to the Merger Agreement, the Company entered into a
Registration Rights Agreement, dated as of February 8, 2008, among the Company
and the Stockholders (the “Agreement”), pursuant to which the Stockholders are
entitled to certain shelf, demand and piggyback registration rights with respect
to the Common Stock as specified therein; and

WHEREAS, the parties to this Amendment wish to amend the Agreement as
hereinafter set forth:

NOW, THEREFORE, in consideration of the premises and the mutual covenants and
conditions hereinafter set forth, and for other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereby
agree as follows:

1. Effectiveness. This Amendment shall be effective as of the date set forth in
the preamble of this Amendment.

2. Amendment to Section 3 Agreement. The first sentence of Section 3(a) of the
Agreement is hereby amended and restated in its entirety to read as follows:

“Within 30 days after the Company receives written notice from the Fidelity
Stockholder or the Wayzata Stockholder requesting the Company to file with the
SEC a Shelf Registration relating to the offer and sale, by the Stockholders
from time to time, of the Registrable Common Shares or, if the Company is not
then eligible to use SEC Form S-3 to register under the Securities Act the offer
and sale by the Stockholders of all Registrable Common Shares, as soon as
reasonably practicable after the Company becomes so eligible, the Company shall
file the Shelf Registration Statement with the SEC and shall use its reasonable
best efforts to cause the Shelf Registration Statement to be declared effective
by the SEC as soon as reasonably

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practicable after filing. No written notice referred to in the first sentence of
this Section 3(a) shall be delivered to the Company prior to May 15, 2008.”

3. Miscellaneous. This Amendment shall not constitute an amendment or
modification of any provision of the Agreement not expressly referred to in
Section 2 of this amendment. Except as expressly set forth in this Amendment,
the terms, provisions and conditions of the Agreement shall remain unchanged and
in full force and effect. This Amendment may be executed in counterparts, all of
which shall together constitute a single agreement.

4. Governing Law. THIS AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH
THE LAWS OF THE STATE OF NEW YORK WITHOUT GIVING EFFECT TO ITS PRINCIPLES OR
RULES OF CONFLICT OF LAWS TO THE EXTENT SUCH PRINCIPLES OR RULES WOULD REQUIRE
OR PERMIT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION.

 

2

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IN WITNESS WHEREOF, the parties have executed this Amendment as of the date set
forth in the preamble hereof.

 

COMPANY:

 

PAETEC HOLDING CORP.

By:   /s/ Arunas A. Chesonis Name:   Arunas A. Chesonis Title:  

Chairman, President and Chief

    Executive Officer

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STOCKHOLDERS: Fidelity Stockholder: FIDELITY ADVISOR SERIES II: FIDELITY ADVISOR
HIGH INCOME ADVANTAGE FUND By:   /s/ Peter L. Lydecker

Name:

Title:

 

Peter L. Lydecker

Assistant Treasurer

 

 

 

COMMONWEALTH OF MASSACHUSETTS PENSION RESERVES INVESTMENT MANAGEMENT BOARD By:  
Pyramis Global Advisors Trust Company, as Investment Manager, under Power of
Attorney By:   /s/ Geoffrey W. Johnson

Name:

Title:

 

Geoffrey W. Johnson

Vice President

 

 

 

PENSION INVESTMENT COMMITTEE OF GENERAL MOTORS FOR GENERAL MOTORS EMPLOYEES
DOMESTIC GROUP PENSION TRUST By:   Pyramis Global Advisors Trust Company, as
Investment Manager, under Power of Attorney By:   /s/ Geoffrey W. Johnson

Name:

Title:

 

Geoffrey W. Johnson

Vice President

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FIDELITY SECURITIES FUND: FIDELITY LEVERAGED COMPANY STOCK FUND By:   /s/ Peter
L. Lydecker

Name:

Title:

 

Peter L. Lydecker

Assistant Treasurer

 

 

FIDELITY ADVISOR SERIES I: FIDELITY ADVISOR LEVERAGED COMPANY STOCK FUND By:  
/s/ Peter L. Lydecker

Name:

Title:

 

Peter L. Lydecker

Assistant Treasurer

 

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Wayzata Stockholder: WAYLAND DISTRESSED OPPORTUNITIES
FUND I-B, LLC By:   Wayzata Investment Partners LLC, its Manager By:   /s/ John
D. McEvoy

Name:

Title:

 

John D. McEvoy

Authorized Signatory

 

 

 

WAYLAND DISTRESSED OPPORTUNITIES
FUND I-C, LLC By:   Wayzata Investment Partners LLC, its Manager By:   /s/ John
D. McEvoy

Name:

Title:

 

John D. McEvoy

Authorized Signatory

 

 

 

WAYZATA OPPORTUNITIES FUND, LLC By:   Wayzata Investment Partners LLC, its
Manager By:   /s/ John D. McEvoy

Name:

Title:

 

John D. McEvoy

Authorized Signatory

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WAYZATA OPPORTUNITIES FUND
OFFSHORE, L.P. By:   Wayzata Offshore GP, LLC, its General Partner By:   Wayzata
Investment Partners LLC, its Manager By:   /s/ John D. McEvoy

Name:

Title:

 

John D. McEvoy

Authorized Signatory

 

 

 

 

WAYZATA RECOVERY FUND, LLC By:   Wayzata Investment Partners LLC, its Manager
By:   /s/ John D. McEvoy

Name:

Title:

 

John D. McEvoy

Authorized Signatory