diff --git a/mkosi.extra/usr/lib/systemd/system/kde-linux-flatpak.service b/mkosi.extra/usr/lib/systemd/system/kde-linux-flatpak.service
new file mode 100644
index 0000000..ca213d7
--- /dev/null
+++ b/mkosi.extra/usr/lib/systemd/system/kde-linux-flatpak.service
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+# SPDX-FileCopyrightText: 2024 Harald Sitter <sitter@kde.org>
+
+[Unit]
+Description=Initial Flatpaks Seeding
+
+[Service]
+ExecStart=/usr/bin/flatpak install --noninteractive --assumeyes --sideload-repo=/system/@flatpak/.ostree/repo flathub org.mozilla.firefox
+
+[Install]
+WantedBy=multi-user.target