diff --git a/Makefile b/Makefile
index fbb641c..435b77f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,2 +1,2 @@
 package:
-	(cd src && zip -r - . -x '*.swp' -x '*.DS_Store') > marinara-`jq -r .version src/manifest.json`.zip
+	ruby make.rb
diff --git a/make.rb b/make.rb
new file mode 100644
index 0000000..d604214
--- /dev/null
+++ b/make.rb
@@ -0,0 +1,13 @@
+unversioned = `git ls-files -o src`.strip
+if !unversioned.empty?
+  puts "Error: Unversioned files in tree, exiting.\n#{unversioned}"
+  exit 1
+end
+
+version = `jq -r .version src/manifest.json`.strip
+if version.empty?
+  puts 'Error: Package version not found in manifest.json, exiting.'
+  exit 1
+end
+
+`(cd src && zip -r - . -x '*.swp' -x '*.DS_Store') > marinara-#{version}.zip`