diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
index bebbc80e2bf8dc..804b46e1f47d8d 100644
--- a/lib/_stream_readable.js
+++ b/lib/_stream_readable.js
@@ -211,7 +211,7 @@ function howMuchToRead(n, state) {
   if (state.objectMode)
     return n === 0 ? 0 : 1;
 
-  if (n === null || isNaN(n)) {
+  if (n === null || n !== n) {
     // only flow one buffer at a time
     if (state.flowing && state.buffer.length)
       return state.buffer[0].length;