SIXTH AMENDMENT TO LEASE AGREEMENT

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Exhibit 10.31

SIXTH AMENDMENT TO LEASE AGREEMENT

        THIS SIXTH AMENDMENT TO LEASE AGREEMENT (the " Amendment ") made this 6 ^th  day of August, 2008 between DAN ROAD BUILDING LLC, a Delaware limited liability company, with an address in care of Great Point Investors LLC, Two Center Plaza, Suite 410, Boston, MA 02108 (" Landlord ") and NETWORK ENGINES, INC., a Delaware corporation, with an address of 15 Dan Road, Canton, MA 02021 (" Tenant ").

        WHEREAS, New Boston Batterymarch Limited Partnership, Landlord's predecessor-in-interest, and Tenant entered into a Lease Agreement dated October 19, 1999, as amended by a First Amendment to Lease Agreement dated February 1, 2000, a Second Amendment to Lease Agreement dated June 1, 2000, a Third Amendment to Lease Agreement dated September 14, 2000, a Fourth Amendment to Lease Agreement dated October 20, 2003 and a Fifth Amendment to Lease Agreement dated July 20, 2006 (as amended, the " Lease "), pursuant to which Tenant leases approximately 51,935 rentable square feet at 15 Dan Road, Canton, Massachusetts (the " Premises ");

        WHEREAS, Tenant desires to extend the initial term of the Lease for the Premises through March 30, 2012, and Landlord has agreed to such extension on the terms and conditions set forth herein; and

        WHEREAS, Landlord and Tenant desire to memorialize their understanding and modify the Lease consistent therewith.

        NOW, THEREFORE, in consideration of the mutual covenants herein contained, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant agree that the Lease shall be amended as follows:

        1.      Term .    The Lease Term shall be extended so as to include the period from April 1, 2009 (the " Extension Commencement Date ") through March 31, 2012.

        2.      Rent .    Annual base Rent for such extended period shall be as follows: April 1, 2009 through March 31, 2012: $714,106.25 per annum ($59,508.85 per month).

        3.      Security Deposit .    As a condition to the effectiveness of this Amendment, on or before October 31, 2008, Tenant shall deliver to Landlord an amendment to Letter of Credit No. SVB00IS1965 issued by Silicon Valley Bank, modifying the expiration date of such Letter of Credit to April 30, 2012.

        4.      Renewal Option .    Tenant shall have the following option to extend the Term of the Lease beyond March 31, 2012:

        Provided that Tenant is not in default beyond any applicable grace or cure period hereunder, Tenant shall have the right to extend the term of this Lease for one (1) additional term of two (2) years (the " Extended Term ") commencing on April 1, 2012. Tenant shall exercise the right to extend the term of this Lease by written notice to Landlord no later than June 30, 2011. The Rent for the Extended Term shall be the greater of the then current Rent or the Market Rent as hereinafter defined. The " Market Rent " shall be determined by Landlord based on leases then currently under negotiation or recently executed for the Property. If no such leases are under negotiation or have been recently executed, then the Market Rent shall be reasonably determined by Landlord based on comparable office space in the town or city in which the Premises are located (if any such space exists) taking into account, among other factors, amenities, setting, location and demographics. Landlord shall notify Tenant of the Market Rent within a reasonable period after Tenant notifies Landlord that Tenant is exercising the option to extend, provided Landlord shall not be required to set the Market Rent prior to ten (10) months before the expiration of the Term. If Tenant disagrees with Landlord's determination of the Market Rent and the parties are unable to agree upon a Market Rent within thirty (30) days after Landlord's notice thereof, then the Market Rent shall be determined by appraisal

made as hereinafter provided by a board of three (3) reputable independent commercial real estate brokers, each of whom shall have at least ten (10) years of experience in the Greater Boston office rental market and each of whom is hereinafter referred to as an "appraiser." Tenant and Landlord shall each appoint one such appraiser and the two (2) appraisers so appointed shall appoint the third appraiser. The cost and expenses of each appraiser