diff --git a/package.json b/package.json
index 4e8f8566..e16f6d81 100644
--- a/package.json
+++ b/package.json
@@ -72,6 +72,7 @@
     "webpack": "2.6.1"
   },
   "scripts": {
+    "prepublishOnly": "echo \"Error: must publish from dist/\" && exit 1",
     "test": "jest",
     "test-integration": "jest tests_integration",
     "lint": "cross-env EFF_NO_LINK_RULES=true eslint . --format node_modules/eslint-friendly-formatter",
diff --git a/scripts/build/build.js b/scripts/build/build.js
index a0a08afa..22a3fb2a 100755
--- a/scripts/build/build.js
+++ b/scripts/build/build.js
@@ -123,6 +123,10 @@ shell.cp("node_modules/sw-toolbox/sw-toolbox.js", `${docs}/sw-toolbox.js`);
 shell.echo("Copy package.json");
 const pkgWithoutDependencies = Object.assign({}, pkg);
 delete pkgWithoutDependencies.dependencies;
+pkgWithoutDependencies.scripts = {
+  prepublishOnly:
+    "node -e \"assert.equal(require('.').version, require('..').version)\""
+};
 pipe(JSON.stringify(pkgWithoutDependencies, null, 2)).to("dist/package.json");
 
 shell.echo("Copy README.md");