diff --git a/debian/freedombox.preinst b/debian/freedombox.preinst
new file mode 100755
index 000000000..c10163861
--- /dev/null
+++ b/debian/freedombox.preinst
@@ -0,0 +1,27 @@
+#!/bin/sh
+
+set -e
+
+case "$1" in
+    upgrade)
+        # Handle removing freedombox-setup-repositories.timer from 20.5.
+        if dpkg --compare-versions "$2" le 20.7; then
+            if [ -x "/usr/bin/deb-systemd-invoke" ]; then
+               deb-systemd-invoke stop freedombox-setup-repositories.timer >/dev/null 2>/dev/null || true
+            fi
+
+            if [ -x "/usr/bin/deb-systemd-helper" ]; then
+                deb-systemd-helper purge freedombox-setup-repositories.timer >/dev/null || true
+                deb-systemd-helper unmask freedombox-setup-repositories.timer >/dev/null || true
+            fi
+
+            if [ -d /run/systemd/system ]; then
+                systemctl daemon-reload
+            fi
+        fi
+        ;;
+esac
+
+#DEBHELPER#
+
+exit 0