--- ./d-i/source/partman-crypto/check.d/unsafe_swap 2015-12-22 13:11:28.000000000 -0800
+++ ./d-i/source/partman-crypto/check.d/detects_zram    2017-06-30 18:38:36.170316257 -0700
@@ -31,12 +31,18 @@
    if echo $device | grep -q "^/dev/mapper/"; then
        if dm_is_safe "$device"; then
            continue
        fi
    fi

+   # zram isn't disk-backed swap, so unsafe_swap doesn't
+   # straightforwardly apply
+   if echo $device | grep -q "^/dev/zram"; then
+       continue
+   fi
+
    partitions=
    open_dialog PARTITIONS
    while { read_line num id size type fs path name; [ "$id" ]; }; do
        [ "$fs" != free ] || continue
        partitions="$partitions $id"
    done