Exhibit 99.1

FOR IMMEDIATE RELEASE NEWS RELEASE

Date Submitted: July 21, 2005
NASDAQ Symbol: FBMI Contact: Samuel G. Stone
Executive Vice President and
Chief Financial Officer
(989) 466-7325

FIRSTBANK CORPORATION ANNOUNCES
SECOND QUARTER AND YEAR-TO-DATE 2005 RESULTS

Highlights Include:
•	Earnings per share (diluted) of $0.46 for the second quarter of 2005, compared to $0.39 in the first quarter of 2005 and $0.43 in the second quarter of 2004
•	Earnings per share (diluted) of $0.85 in the first half of 2005 compared to $0.87 in the first half on 2004
•	Keystone Community Bank acquisition continues on track
•	Addition to Russell Microcap Index

Alma, Michigan (FBMI) — Thomas R. Sullivan, President and Chief Executive Officer of Firstbank Corporation announced earnings per share of $0.46 for the second quarter of 2005, compared to $0.43 for the second quarter of 2004, an increase of 7.0%. Net income was $2,508,000 for the quarter ended June 30, 2005, compared to $2,565,000 for the quarter ended June 30, 2004. Returns on average assets and average equity for the second quarter of 2005 were 1.23% and 13.6%, respectively, compared with 1.33% and 12.2%, respectively, in the second quarter of 2004. Net income was affected by mortgage activity at a much lower level than year-ago, with gain on sale of mortgages down 49%. The capital management strategies of share repurchase and self tender offer executed primarily in 2004 helped improve earnings per share and return on equity. All per share amounts are fully diluted amounts and have been adjusted to reflect the 5% stock dividend paid in December 2004.

For the first half of 2005, earnings per share of $0.85 compared to $0.87 for the first half of 2004, a decrease of 2.3%. Net income was $4,645,000 for the six months ended June 30, 2005, compared to $5,246,000 for the six months ended June 30, 2004. Returns on average assets and average equity for the first half of 2005 were 1.16% and 12.8%, respectively, compared with 1.35% and 12.3%, respectively, in the first half of 2004. Firstbank’s capital management strategies helped earnings per share and contributed to the increase in return on equity compared to the year-ago period.

Growth in Firstbank’s balance sheet continued as total assets reached $831 million, 5.7% above the year-ago level. Total portfolio loans at the end of the second quarter of 2005 were 5.3% above the level at June 30, 2004. Commercial and commercial real estate loan growth was strong, increasing 9.1% above the year-ago level, and residential mortgage loans increased 9.9%. Total deposits as of June 30, 2005, were 5.9% above the year-ago level, with savings deposits increasing 33.4% as a result of in-market promotions and with non-interest bearing deposits increasing 4.0% over this time period.

Firstbank’s net interest margin, at 4.39% in the second quarter of 2005, was within 0.02% of the 4.41% level achieved in both the first quarter of 2005 and the second quarter of 2004. Rising rates in Firstbank’s variable rate commercial loan portfolio were offset by lower rates achieved on new and renewed fixed rate loans.

Mr. Sullivan stated, “We are pleased to see earnings growth from our core banking business taking the place of the unusually strong earnings that characterized the mortgage boom of the past few years. Our bankers are doing an excellent job of meeting customer needs in our markets and containing costs. At the same time, we are investing in systems and training designed to increase our service to customers and our revenues in the future. We are also very excited about the opportunity to extend our brand of community banking to the Kalamazoo market as Keystone Community Bank joins our company later this year. Keystone is an excellent and well respected community bank in a market that holds significant opportunity for growth.”

Sullivan continued, “We have been informed that our stock will be part of the new Russell Microcap Index. This new index debuted on July 1 and is comprised of the smallest 1,000 securities in the small-cap Russell 2000 Index along with the next smallest 1,000 companies. While we won’t know the impact of increased exposure of our stock through the Microcap Index for some time, we are hopeful that the combination of increased exposure for our stock, good and progressing fundamental financial performance, and the acquisition of good quality growth opportunities will support creation of value for our shareholders.”

Total non-interest expenses in the second quarter of 2005 declined 1.7% from the first quarter of 2005 and were just 3.2% above the level in the second quarter of 2004. Salaries and employee benefits expense declined 1.3% compared to the first quarter of 2005 and declined 0.1% compared to the second quarter of 2004.

Supported by growth in loans and earning assets, net interest income in the second quarter of 2005 increased 4.8% from the level in the second quarter of 2004. The reduction in mortgage activity compared to last year continued to negatively impact earnings comparisons, as gain on sale of mortgage loans showed a 49% decline compared to the second quarter of 2004. Although total non-interest income in the second quarter of 2005 declined 8.5% from the year-ago quarter, it increased 16.6% compared to the first quarter of 2005. Helping to offset the decline in mortgage activity was an 11.2% increase in deposit account fee income for the first half of 2005 compared to the first half of 2004.

Primarily as a result of the self tender offer in 2004, shareholders’ equity decreased 13.0% from June 30, 2004 to June 30, 2005. Since December 31, 2004, shareholder’s equity has increased 3.5%. Firstbank did not repurchase shares in the second quarter of 2005, as capital is being maintained at an appropriate level in consideration of the pending acquisition of Keystone Financial Corporation. The ratio of average equity to average assets stood at 9.0% in the second quarter of 2005, compared to 9.2% in the first quarter of 2005 and 10.9% in the second quarter of 2004.

Firstbank’s mortgage servicing portfolio was $472.8 million as of June 30, 2005, compared to $473.9 million at March 31, 2005, and $471.1 million at June 30, 2004.

Firstbank’s asset quality measures remained strong. Net charge-offs declined, to $106,000 in the second quarter of 2005, or 0.06% annualized as a percentage of average loans, compared to $461,000, or 0.28% annualized as a percentage of average loans in the first quarter of 2005 and compared to $119,000, or 0.07% annualized, in the second quarter of 2004. The ratio of non-performing loans to loans was 0.41% as of June 30, 2005, compared to 0.23% at March 31, 2005, and 0.37% at June 30, 2004. The increase in non-performing loans was primarily related to one loan which has little risk of loss due to a government guarantee. These measures of asset quality continue to be at levels considered in the industry to be favorable.

Firstbank Corporation, headquartered in Alma, Michigan is currently a five bank financial services company with assets of $831 million and 35 banking offices located in central and northeast Michigan. Bank subsidiaries include: Firstbank — Alma; Firstbank (Mt. Pleasant); Firstbank — West Branch; Firstbank - Lakeview; and Firstbank — St. Johns. Firstbank Corporation’s pending acquisition of the $151 million asset Keystone Community Bank in Kalamazoo, Michigan, is expected to close in the fourth quarter of 2005, subject to regulatory and Keystone shareholder approvals. Other corporate affiliates include 1^st Armored, Inc.; 1^st Title; Gladwin Land Company, Inc.; and C. A. Hanes Realty, Inc. Investment services are available through affiliations with CB Wealth Management N.A., MML Investors Services, Inc., and Raymond James Financial Services Inc.

This press release contains certain forward-looking statements that involve risks and uncertainties. When used in this press release the words “anticipate,” “believe,” “expect,” “hopeful,” “potential,” “should,” and similar expressions identify forward-looking statements. Forward-looking statements include, but are not limited to, statements concerning future business growth, increases in interest rates and positioning of balance sheets to benefit net interest margins and earnings. Such statements are subject to certain risks and uncertainties which could cause actual results to differ materially from those expressed or implied by such forward-looking statements, including, but not limited to, economic, competitive, governmental and technological factors affecting the Company’s operations, markets, products, services, interest rates and fees for services. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release.

FIRSTBANK CORPORATION
CONSOLIDATED STATEMENTS OF INCOME
(Dollars in thousands except per share data)
UNAUDITED

	Three months Ended									Six months Ended:
	Jun 30 2005			Mar 31 2005			Jun 30 2004			Jun 30 2005			Jun 30 2004
Interest income:
Interest and fees on loans	$	11,353		$	10,847		$	10,058		$	22,200		$	20,238
Investment securities
Taxable		504			458			380		$	962		$	763
Exempt from federal income tax		231			248			228			479			470
Short term investments		30			34			32			64			56
Total interest income		12,118			11,587			10,698			23,705			21,527
Interest expense:
Deposits		2,617			2,243			1,815			4,860			3,601
Notes payable and other borrowing		1,237			1,196			995			2,433			2,025
Total interest expense		3,854			3,439			2,810			7,293			5,626
Net interest income		8,264			8,148			7,888			16,412			15,901
Provision for loan losses		73			8			60			81			(131	)
Net interest income after provision for loan losses		8,191			8,140			7,828			16,331			16,032
Noninterest income:
Gain on sale of mortgage loans		431			455			847			886			1,631
Service charges on deposit accounts		783			720			703			1,503			1,352
Gain on sale of securities		17			12			11			29			11
Mortgage servicing		30			48			(56	)		78			(76	)
Other		1,336			978			1,316			2,314			2,268
Total noninterest income		2,597			2,213			2,821			4,810			5,186
Noninterest expense:
Salaries and employee benefits		3,836			3,887			3,838			7,723			7,779
Occupancy and equipment		969			1,016			923			1,985			1,892
Amortization of intangibles		75			76			75			151			151
FDIC insurance premium		21			21			21			42			43
Other		2,193			2,216			2,014			4,409			3,609
Total noninterest expense		7,094			7,216			6,871			14,310			13,474
Income before federal income taxes		3,694			3,137			3,778			6,831			7,744
Federal income taxes		1,186			1,000			1,213			2,186			2,498
Net Income	$	2,508		$	2,137		$	2,565		$	4,645		$	5,246
Fully Tax Equivalent Interest Income	$	8,398		$	8,292		$	8,014		$	16,767		$	16,225
Per Share Data:
Basic Earnings	$	0.47		$	0.40		$	0.44		$	0.87		$	0.89
Diluted Earnings	$	0.46		$	0.39		$	0.43		$	0.85		$	0.87
Dividends Paid	$	0.22		$	0.21		$	0.20		$	0.43		$	0.39
Performance Ratios:
Return on Average Assets*		1.23	%		1.09	%		1.33	%		1.16	%		1.35	%
Return on Average Equity*		13.6	%		11.8	%		12.2	%		12.8	%		12.3	%
Net Interest Margin (FTE) *		4.39	%		4.41	%		4.41	%		4.41	%		4.46	%
Book Value Per Share+	$	14.10		$	13.76		$	14.70		$	14.10		$	14.70
Average Equity/Average Assets		9.0	%		9.2	%		10.9	%		9.1	%		10.9	%
Net Charge-offs		106			461			119			567			754
Net Charge-offs as a % of Average Loans^*		0.06	%		0.28	%		0.07	%		0.17	%		0.08	%
* Annualized
+ Period End
^ Total loans less loans held for sale

FIRSTBANK CORPORATION
CONSOLIDATED BALANCE SHEETS
(Dollars in thousands)
UNAUDITED

	Jun 30 2005			Mar 31 2005			Dec 31 2004			Jun 30 2004
ASSETS
Cash and cash equivalents:
Cash and due from banks	$	26,541		$	21,930		$	23,715		$	24,070
Short term investments		4,826			1,849			2,057			10,807
Total cash and cash equivalents		31,367			23,779			25,772			34,877
Securities available for sale		77,803			77,855			72,475			66,256
Federal Home Loan Bank stock		5,563			5,412			5,355			5,241
Loans:
Loans held for sale		1,533			1,786			1,969			1,400
Portfolio loans:
Commercial		104,761			107,211			110,261			101,393
Commercial real estate		242,321			235,040			225,372			216,689
Residential mortgage		243,718			240,281			231,213			221,766
Real estate construction		37,793			37,877			47,920			51,442
Consumer		55,166			52,708			54,491			57,944
Credit card		1,799			1,785			1,830			1,828
Total portfolio loans		685,558			674,902			671,087			651,062
Less allowance for loan losses		(10,094	)		(10,128	)		(10,581	)		(11,232	)
Net portfolio loans		675,464			664,774			660,506			639,830
Premises and equipment, net		17,126			17,323			17,658			17,923
Goodwill		4,465			4,465			4,465			4,880
Other intangibles		2,245			2,296			2,395			2,538
Other assets		15,121			16,486			15,540			13,111
TOTAL ASSETS	$	830,687		$	814,176		$	806,135		$	786,056
LIABILITIES AND SHAREHOLDERS' EQUITY
LIABILITIES
Deposits:
Noninterest bearing accounts		109,269			99,424			106,208			105,104
Interest bearing accounts:
Demand		160,576			173,542			177,067			181,272
Savings		131,589			115,234			100,277			98,651
Time		222,420			230,425			219,715			204,341
Total deposits		623,854			618,625			603,267			589,368
Securities sold under agreements to
repurchase and overnight borrowings		34,374			31,855			39,100			28,883
FHLB Advances and notes payable		76,256			68,899			71,430			72,475
Subordinated Debt		10,310			10,310			10,310			0
Accrued interest and other liabilities		10,472			11,214			9,164			8,641
Total liabilities		755,266			740,903			733,271			699,367
SHAREHOLDERS' EQUITY
Preferred stock; no par value, 300,000
shares authorized, none issued
Common stock; 20,000,000 shares authorized *		65,155			64,533			64,713			74,115
Retained earnings		10,166			8,835			7,816			12,139
Accumulated other comprehensive income		100			(95	)		335			435
Total shareholders' equity		75,421			73,273			72,864			86,689
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$	830,687		$	814,176		$	806,135		$	786,056
* Common stock shares issued and outstanding		5,350,816			5,326,667			5,322,137			5,895,985
Asset Quality Ratios:
Non-Performing Loans / Loans^		0.41	%		0.23	%		0.28	%		0.37	%
Non-Perf. Loans + OREO / Loans^ + OREO		0.54	%		0.36	%		0.42	%		0.39	%
Non-Performing Assets / Total Assets		0.45	%		0.30	%		0.35	%		0.33	%
Allowance for Loan Loss as a % of Loans^		1.47	%		1.50	%		1.58	%		1.73	%
Allowance / Non-Performing Loans		356	%		645	%		568	%		464	%
Quarterly Average Balances:
Total Portfolio Loans^	$	678,835		$	670,240		$	663,475		$	644,714
Total Earning Assets	$	765,888		$	755,795		$	746,814		$	729,187
Total Shareholders' Equity		74,009			74,881			72,021			84,977
Total Assets		821,362			812,067			799,688			779,826
Diluted Shares Outstanding		5,425,421			5,436,709			5,420,497			5,993,298
^ Total loans less loans held for sale