diff --git a/packages/xarc-app-dev/package.json b/packages/xarc-app-dev/package.json
index 86620bd96..420417a14 100644
--- a/packages/xarc-app-dev/package.json
+++ b/packages/xarc-app-dev/package.json
@@ -94,7 +94,7 @@
     "webpack-dev-middleware": "^3.7.2",
     "webpack-hot-middleware": "^2.25.0",
     "winston": "^2.4.4",
-    "xaa": "^1.6.2",
+    "xaa": "^1.7.0",
     "xenv-config": "^1.3.1",
     "xsh": "^0.4.5"
   },
diff --git a/packages/xarc-app-dev/scripts/l10n/flatten-messages.js b/packages/xarc-app-dev/scripts/l10n/flatten-messages.js
index 56e07cfcd..fa1da19f8 100644
--- a/packages/xarc-app-dev/scripts/l10n/flatten-messages.js
+++ b/packages/xarc-app-dev/scripts/l10n/flatten-messages.js
@@ -10,6 +10,7 @@ const getFilePaths = Util.promisify(require("glob"));
 const MESSAGES_PATTERN = "./tmp/messages/**/*.json";
 const RAW_MESSAGES_DIR = "./dist/";
 const RAW_MESSAGES_NAME = "raw-messages.json";
+const xaa = require("xaa");
 
 /**
  * @param  {String}  filePath  The file path
@@ -37,15 +38,14 @@ function readFileAsJSON(filePath) {
  * @return  {Promise}  A promise that resolves to a flat POJO with the default messages extracted
  *                     from all files
  */
-function getAllDefaultMessages(messageFilesPathPattern) {
-  return getFilePaths(messageFilesPathPattern)
-    .map(readFileAsJSON)
-    .reduce((previousValue, defaultMessageDescriptors) => {
-      defaultMessageDescriptors.forEach(descriptor => {
-        previousValue[descriptor.id] = descriptor;
-      });
-      return previousValue;
-    }, {});
+async function getAllDefaultMessages(messageFilesPathPattern) {
+  const fileJsons = await xaa.map(await getFilePaths(messageFilesPathPattern), readFileAsJSON);
+  return fileJsons.reduce((previousValue, defaultMessageDescriptors) => {
+    defaultMessageDescriptors.forEach(descriptor => {
+      previousValue[descriptor.id] = descriptor;
+    });
+    return previousValue;
+  }, {});
 }
 
 const writeRawMessages = _.partial(writeFileAsJSON, RAW_MESSAGES_DIR, RAW_MESSAGES_NAME);