diff --git a/Makefile b/Makefile
index f88841cff..d0b426c47 100644
--- a/Makefile
+++ b/Makefile
@@ -192,8 +192,8 @@ testbuilds/$(name)$1.crx.zip : \
  package.json version.json tools/zip-crx.js node_modules/jszip/package.json
 	node tools/zip-crx.js $1
 
-testbuilds/$(name)$1.crx : testbuilds/$(name)$1.crx.zip package.json tools/sign.js node_modules/node-rsa/package.json
-	node tools/sign.js $1
+testbuilds/$(name)$1.crx : $(foreach f,$(crx_contents),testbuilds/crx$1/$(f)) version.json tools/sign.sh | tmp
+	tools/sign.sh $1
 
 testbuilds/$(name)$1.meta.js : src/meta/metadata.js src/meta/icon48.png version.json src/Archive/archives.json $(template_deps) | testbuilds
 	$(template) $$< $$@ type=userscript channel=$1
diff --git a/crx-chromium-version.txt b/crx-chromium-version.txt
new file mode 100644
index 000000000..2d4f0bd7a
--- /dev/null
+++ b/crx-chromium-version.txt
@@ -0,0 +1 @@
+Chromium 73.0.3683.75 built on Debian buster/sid, running on Debian buster/sid
diff --git a/tools/sign.sh b/tools/sign.sh
new file mode 100755
index 000000000..fc856cc37
--- /dev/null
+++ b/tools/sign.sh
@@ -0,0 +1,8 @@
+#!/bin/bash
+channel=$1
+mkdir -p tmp-crx
+cp -r "testbuilds/crx$channel" "tmp-crx/crx$channel"
+touch -d "$(jq -r '.date' version.json)" "tmp-crx/crx$channel"/*
+chromium --pack-extension="tmp-crx/crx$channel" --pack-extension-key="$(dirname "$PWD")/4chan-x.keys/4chan-X.pem"
+mv "tmp-crx/crx$channel.crx" "testbuilds/4chan-X$channel.crx"
+rm -r 'tmp-crx/'