diff --git a/lib/static.js b/lib/static.js
index d4b1506..e866b53 100644
--- a/lib/static.js
+++ b/lib/static.js
@@ -65,11 +65,11 @@ const copyAssetsAndWriteFile = async (sourceDir, file, targetDir) => {
 
   let image;
   const html = md.marked(markdown.toString());
-  while (image = htmlImageRE.exec(html)) {
+  while ((image = htmlImageRE.exec(html))) {
     const [, imgPath] = image;
     if (!isAbsoluteURL(imgPath)) {
       const relPath = path.join(path.dirname(file), imgPath);
-      awaits.push(cp(path.join(sourceDir, relPath), path.join(targetDir, relPath)).catch((err) => console.warn(err)));
+      awaits.push(cp(path.join(sourceDir, relPath), path.join(targetDir, relPath)).catch(err => console.warn(err)));
     }
   }