Washington United for Marriage, the coalition working to uphold the state’s marriage equality law in next month’s referendum, announced a $500,000 donation from Bill and Melinda Gates in support of their efforts. According to the Seattle Post-Intelligencer, the Gates’ donation was made on October 15, but didn’t post to the website of the state’s Public Disclosure Commission until yesterday.

Including this latest contribution, Bill and Melinda Gates have contributed $600,000 to defend marriage equality in Washington State. The Post-Intelligencer reports that Washington United has raised nearly $11 million so far, while opponents of equal marriage rights have raised a little over $2 million.