diff --git a/lib/node-progress.js b/lib/node-progress.js
index 2b62641..b9de1cc 100644
--- a/lib/node-progress.js
+++ b/lib/node-progress.js
@@ -52,7 +52,10 @@ function ProgressBar(fmt, options) {
   } else {
     options = options || {};
     if ('string' != typeof fmt) throw new Error('format required');
-    if ('number' != typeof options.total) throw new Error('total required');
+    if (
+      'number' != typeof options.total
+      || isNaN(options.total)
+    ) throw new Error('total of number format required');
   }
 
   this.fmt = fmt;