ADDENDUM TO STOCK OPTION AGREEMENT

Exhibit 10.4

ADDENDUM

TO

STOCK OPTION AGREEMENT

The following provisions are hereby incorporated into, and are hereby made a part of, that certain Stock Option Agreement (the “Option Agreement”) by and between U.S. Auto Parts Network, Inc. (the “Corporation”) and                          (“Optionee”) evidencing the stock option (the “Option”) granted on this date to Optionee under the terms of the Corporation’s 2006 Equity Incentive Plan, and such provisions shall be effective immediately. All capitalized terms in this Addendum, to the extent not otherwise defined herein, shall have the meanings assigned to them in the Option Agreement.

INVOLUNTARY TERMINATION FOLLOWING

A CHANGE IN CONTROL

1. If the Option is to be assumed by the successor corporation (or the parent thereof) in connection with a Change in Control or is otherwise to be continued in full force and effect pursuant to the terms of the Change in Control transaction, then none of the Option Shares shall vest on an accelerated basis upon the occurrence of that Change in Control, and Optionee shall accordingly continue, over his or her period of Service following the Change in Control, to vest in the Option Shares in one or more installments in accordance with the provisions of the Option Agreement. However, upon an Involuntary Termination of Optionee’s Service within twelve (12) months following such Change in Control, all the Option Shares at the time subject to the Option shall automatically vest in full on an accelerated basis so that the Option shall immediately become exercisable for all the Option Shares as fully-vested shares and may be exercised for any or all of those Option Shares as vested shares. The Option shall remain so exercisable until the earlier of (i) the Expiration Date or (ii) the expiration of the one (1)-year period measured from the date of the Involuntary Termination.

2. For purposes of this Addendum, an Involuntary Termination shall mean the termination of Optionee’s Service by reason of:

(i) Optionee’s involuntary dismissal or discharge by the Corporation for reasons other than for Misconduct, or

(ii) Optionee’s voluntary resignation following (A) a change in Optionee’s position with the Corporation (or Parent or Subsidiary employing Optionee) which materially reduces Optionee’s duties and responsibilities or the level of management to which he or she reports, (B) a reduction in Optionee’s level of compensation (including base salary, fringe benefits and target bonus under any corporate-performance based incentive programs) by more than fifteen percent (15%) or (C) a relocation of Optionee’s place of employment by more than fifty (50) miles, provided and only if such change, reduction or relocation is effected by the Corporation without Optionee’s consent.

3. The provisions of Paragraph 1 of this Addendum shall govern the period for which the Option is to remain exercisable following the Involuntary Termination of Optionee’s Service within twelve (12) months after the Change in Control and shall supersede any provisions to the contrary in Paragraph 5 of the Option Agreement.

IN WITNESS WHEREOF, U.S. Auto Parts Network, Inc. has caused this Addendum to be executed by its duly authorized officer as of the Effective Date specified below.

EFFECTIVE DATE:                     

2.