UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

FORM 8-K

CURRENT REPORT
Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934

Date of Report: October 1, 2005

FIRSTBANK CORPORATION
(Exact Name of Registrant as Specified in Charter)

Michigan
(State or Other Jurisdiction
of Incorporation) 000-14209
(Commission
File Number) 38-2633910
(IRS Employer
Identification No.)

311 Woodworth Avenue
Alma, Michigan
(Address of principal executive office) 48801
(Zip Code)

Registrant’s telephone number, including area code: (989) 463-3131

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[   ]    Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425).
[   ]    Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12).
[   ]    Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240-14d-2(b)).
[   ]    Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)).

ITEM 8.01 OTHER EVENTS

On October 1, 2005, the merger of Keystone Financial Corporation with and into Firstbank Corporation became effective. A copy of the press release announcing the merger is filed as Exhibit 99.1 to this report.

ITEM 9.01 FINANCIAL STATEMENTS AND EXHIBITS

(c) Exhibits.

Exhibit Number		Description
	99.1	Press Release of Firstbank Corporation announcing that the Keystone Financial Corporation merger with and into Firstbank Corporation is effective.

2

SIGNATURE

        Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Dated: October 3, 2005 FIRSTBANK CORPORATION
(Registrant)



By: /s/ Samuel G. Stone
      ——————————————
      Samuel G. Stone
      Chief Financial Officer

3

EXHIBIT INDEX

99.1 Press Release of Firstbank Corporation announcing that the Keystone Financial Corporation merger with and into Firstbank Corporation is effective.

4