Use an icon with a transparent background
As raised by serebit on the ML: https://lists.archlinux.org/archives/list/arch-dev-public@lists.archlinux.org/message/2WM24CZGJ3WQMHQC4TXH3KEZPPOLJKII/
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As raised by serebit on the ML: https://lists.archlinux.org/archives/list/arch-dev-public@lists.archlinux.org/message/2WM24CZGJ3WQMHQC4TXH3KEZPPOLJKII/