2 files changed, 3 insertions, 2 deletions
diff --git a/lib/_stream_transform.js b/lib/_stream_transform.js
index ba80f5c09c..b8d4a7704a 100644
--- a/lib/_stream_transform.js
+++ b/lib/_stream_transform.js
@@ -157,7 +157,7 @@ Transform.prototype.push = function(chunk, encoding) {
 // an error, then that'll put the hurt on the whole operation.  If you
 // never call cb(), then you'll never get another chunk.
 Transform.prototype._transform = function(chunk, encoding, cb) {
-  throw new Error('_transform() is not implemented');
+  throw new errors.Error('ERR_METHOD_NOT_IMPLEMENTED', '_transform');
 };
 
 Transform.prototype._write = function(chunk, encoding, cb) {
diff --git a/lib/_stream_writable.js b/lib/_stream_writable.js
index 7de77958d5..3ac4df7ac4 100644
--- a/lib/_stream_writable.js
+++ b/lib/_stream_writable.js
@@ -33,6 +33,7 @@ const internalUtil = require('internal/util');
 const Stream = require('stream');
 const Buffer = require('buffer').Buffer;
 const destroyImpl = require('internal/streams/destroy');
+const errors = require('internal/errors');
 
 util.inherits(Writable, Stream);
 
@@ -319,7 +320,7 @@ Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {
   if (typeof encoding === 'string')
     encoding = encoding.toLowerCase();
   if (!Buffer.isEncoding(encoding))
-    throw new TypeError('Unknown encoding: ' + encoding);
+    throw new errors.TypeError('ERR_UNKNOWN_ENCODING', encoding);
   this._writableState.defaultEncoding = encoding;
   return this;
 };