diff --git a/ci/umount.sh b/ci/umount.sh
new file mode 100755
index 000000000..400b0e115
--- /dev/null
+++ b/ci/umount.sh
@@ -0,0 +1,17 @@
+#! /bin/sh
+#
+# This is an "unmount" script that tries to unmount whatever
+# filesystems Calamares might have left mounted (e.g. because of
+# a crash, or ^C'ing the installer, or ..).
+#
+
+# Swap may have become enabled on the disks just used; assume
+# we're in a live session where we don't want any.
+sudo swapoff -a
+# In Arch-based systems, there may be a gpg-agent started by
+# pacman during installation, which lives in the chroot. Kill
+# them all; again assume we're in a live session where it doesn't matter.
+sudo pkill gpg-agent
+# Unmount the filesystems in *reverse* order, since we need to ditch
+# e.g. /run/udev before /run before the root filesystem.
+sudo umount $( LC_ALL=C mount | awk '/calamares-root/{print $3}' | LC_ALL=C sort -r )