diff --git a/src/common/optionsUtils.js b/src/common/optionsUtils.js
new file mode 100644
index 0000000..0efb6c9
--- /dev/null
+++ b/src/common/optionsUtils.js
@@ -0,0 +1,28 @@
+import optionsPrototype from './optionsPrototype.json5';
+import specialOptions from './specialOptions.json5';
+
+export {optionsPrototype, specialOptions};
+
+// Adds missing options with their default value. If |dryRun| is set to false,
+// they are also saved to the sync storage area.
+export function cleanUpOptions(options, dryRun = false) {
+  console.log('[cleanUpOptions] Previous options', JSON.stringify(options));
+
+  if (typeof options !== 'object' || options === null) options = {};
+
+  var ok = true;
+  for (const [opt, optMeta] of Object.entries(optionsPrototype)) {
+    if (!(opt in options)) {
+      ok = false;
+      options[opt] = optMeta['defaultValue'];
+    }
+  }
+
+  console.log('[cleanUpOptions] New options', JSON.stringify(options));
+
+  if (!ok && !dryRun) {
+    chrome.storage.sync.set(options);
+  }
+
+  return options;
+}