diff --git a/package.json b/package.json
index 08f8f6d..63226db 100644
--- a/package.json
+++ b/package.json
@@ -5,8 +5,8 @@
   "repository": "shinnn/array-to-sentence",
   "scripts": {
     "pretest": "eslint --config @shinnn browser.js index.js test.js",
-    "test": "node test.js",
-    "coverage": "istanbul cover test.js"
+    "test": "node --strong_mode --throw-deprecation --track-heap-objects test.js",
+    "coverage": "node --strong_mode node_modules/.bin/istanbul cover test.js"
   },
   "license": "MIT",
   "files": [
diff --git a/test.js b/test.js
index 7787713..d835ff4 100755
--- a/test.js
+++ b/test.js
@@ -65,4 +65,4 @@ runTest('require(\'array-to-sentence\')', require('.'));
 global.window = {};
 require('./' + require('./bower.json').main);
 
-runTest('window.arrayToSentence', window.arrayToSentence);
+runTest('window.arrayToSentence', global.window.arrayToSentence);