1 files changed, 10 insertions, 1 deletions
diff --git a/lib/internal/crypto/hash.js b/lib/internal/crypto/hash.js
index eccfb44569..b28f9fca13 100644
--- a/lib/internal/crypto/hash.js
+++ b/lib/internal/crypto/hash.js
@@ -34,7 +34,8 @@ const kFinalized = Symbol('kFinalized');
 function Hash(algorithm, options) {
   if (!(this instanceof Hash))
     return new Hash(algorithm, options);
-  validateString(algorithm, 'algorithm');
+  if (!(algorithm instanceof _Hash))
+    validateString(algorithm, 'algorithm');
   const xofLen = typeof options === 'object' && options !== null ?
     options.outputLength : undefined;
   if (xofLen !== undefined)
@@ -49,6 +50,14 @@ function Hash(algorithm, options) {
 Object.setPrototypeOf(Hash.prototype, LazyTransform.prototype);
 Object.setPrototypeOf(Hash, LazyTransform);
 
+Hash.prototype.copy = function copy(options) {
+  const state = this[kState];
+  if (state[kFinalized])
+    throw new ERR_CRYPTO_HASH_FINALIZED();
+
+  return new Hash(this[kHandle], options);
+};
+
 Hash.prototype._transform = function _transform(chunk, encoding, callback) {
   this[kHandle].update(chunk, encoding);
   callback();