diff --git a/lib/internal/streams/writable.js b/lib/internal/streams/writable.js
index f1664612d4c668..19814ea8d3d730 100644
--- a/lib/internal/streams/writable.js
+++ b/lib/internal/streams/writable.js
@@ -453,7 +453,7 @@ function _write(stream, chunk, encoding, cb) {
   else if (encoding !== 'buffer' && !Buffer.isEncoding(encoding))
     throw new ERR_UNKNOWN_ENCODING(encoding);
 
-  if (cb = null || typeof cb !== 'function')
+  if (cb == null || typeof cb !== 'function')
     cb = nop;
 
   if (chunk === null) {