Blackbaud Inc. shareholders are being asked this week to give the Charleston technology giant's poison pill a dose more potency.

It's not that any unwanted suitors are stalking the company, which is one of the world's largest markers of financial software for the nonprofit industry.

The proposed change to the company's incorporation certificate can be traced back to Blackbaud's transition from a privately held to publicly traded business five years ago. At that time, Hellman & Friedman Capital Partners III LP, part of a big San Francisco-based investment fund, controlled nearly 60 percent of the locally-based company's common shares.

As such, it made sense for Blackbaud to exempt Hellman & Friedman from a corporate-governance rule that can be used to block certain business transactions –- namely hostile takeovers –- with investors that own a 15 percent or better stake.

But Hellman & Friedman has since unwound its position. As a result, Blackbaud wants its former majority owner to be required to abide by the same poison-pill guidelines as everyone else. It says the added protections would benefit shareholders.

"This could make it difficult for Hellman & Friedman to obtain control of us or initiate actions that are opposed by our board of directors, including delaying or impeding a merger, tender offer, or proxy contest or other change of control transaction involving us, even if such actions are favorable to the interests of our stockholders," Blackbaud said in its 2009 proxy statement.

Blackbaud added several other anti-takeover arrows to its quiver in March based on recent legal decisions in Delaware, where it is incorporated. Applying the poison pill to Hellman & Friedman is the final step in that process. Blackbaud's board is asking shareholders to vote in favor of the change at their annual meeting set for Tuesday morning at the company's Daniel Island headquarters.

While Hellman & Friedman is no longer an investor in the company, it still maintains close ties to Blackbaud. Marco W. Hellman, who worked at the investment fund his father founded from 1987 to 2001 and is now an senior adviser, has been chairman of the local software firm for the past decade.