diff --git a/coffee/lib/create-pipes.coffee b/coffee/lib/create-pipes.coffee
index eba2872..9de444b 100644
--- a/coffee/lib/create-pipes.coffee
+++ b/coffee/lib/create-pipes.coffee
@@ -19,7 +19,7 @@ module.exports = ->
   until created
     try
       dir = tmp_dir + '/sync-exec-' + Math.floor Math.random() * 1000000000
-      fs.mkdir dir
+      fs.mkdirSync dir
       created = true
 
     timeout t_limit, 'Can not create sync-exec directory'
diff --git a/js/lib/create-pipes.js b/js/lib/create-pipes.js
index 341169d..4de65ec 100644
--- a/js/lib/create-pipes.js
+++ b/js/lib/create-pipes.js
@@ -20,7 +20,7 @@
     while (!created) {
       try {
         dir = tmp_dir + '/sync-exec-' + Math.floor(Math.random() * 1000000000);
-        fs.mkdir(dir);
+        fs.mkdirSync(dir);
         created = true;
       } catch (_error) {}
       timeout(t_limit, 'Can not create sync-exec directory');