diff --git a/tools/pack-disk.sh b/tools/pack-disk.sh
new file mode 100755
index 0000000..4ccb2b2
--- /dev/null
+++ b/tools/pack-disk.sh
@@ -0,0 +1,9 @@
+#!/usr/bin/env sh
+# Produce the images zip that CI's DISK_URL secret should point at.
+# Inverse of download-disk.sh: flat archive of windows95.img + default-state.bin.
+set -e
+OUT="${1:-images_$(date +%Y%m%d).zip}"
+cd images
+zip -9 "../$OUT" windows95.img default-state.bin
+cd -
+ls -lh "$OUT"