diff --git a/Firefox.zip b/Firefox.zip
new file mode 100644
index 0000000..3c45f1f
Binary files /dev/null and b/Firefox.zip differ
diff --git a/preseed.cfg b/preseed.cfg
index b934651..6813601 100644
--- a/preseed.cfg
+++ b/preseed.cfg
@@ -53,6 +53,7 @@ d-i pkgsel/include string \
     sudo \
     cage \
     firefox-esr \
+    unzip \
     curl
 
 d-i pkgsel/exclude string gnome-software
@@ -64,4 +65,5 @@ d-i finish-install/reboot_in_progress note
 d-i preseed/late_command string \
     in-target curl -o /tmp/post_install.sh https://git.hamburg.ccc.de/ViMaSter/preseed/raw/branch/main/post_install.sh; \
     in-target chmod +x /tmp/post_install.sh; \
-    in-target /tmp/post_install.sh
+    in-target /tmp/post_install.sh; \
+    in-target sh -c 'FIREFOX_ZIP_URL="${FIREFOX_ZIP_URL:-https://git.hamburg.ccc.de/Firefox.zip}"; mkdir -p /home/kiosk/.mozilla/firefox; curl -fsSL -o /tmp/Firefox.zip "$FIREFOX_ZIP_URL"; unzip -o /tmp/Firefox.zip -d /home/kiosk/.mozilla/firefox; chown -R kiosk:kiosk /home/kiosk/.mozilla/firefox; rm -f /tmp/Firefox.zip'