diff --git a/run-firefox-spike.sh b/run-firefox-spike.sh
new file mode 100755
index 0000000..c69079a
--- /dev/null
+++ b/run-firefox-spike.sh
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+firefox_tree="${script_dir}/../browsec-firefox"
+firefox_binary="${firefox_tree}/obj-x86_64-pc-linux-gnu/dist/bin/firefox"
+
+if [[ ! -x "${firefox_binary}" ]]; then
+  echo "Browsec Firefox build not found at:" >&2
+  echo "  ${firefox_binary}" >&2
+  echo "Build it first with: cd '${firefox_tree}' && ./mach build" >&2
+  exit 1
+fi
+
+if (( $# == 0 )); then
+  set -- https://expired.badssl.com
+fi
+
+cd "${firefox_tree}"
+exec ./mach run --temp-profile "$@"