diff --git a/lib/internal/crypto/sig.js b/lib/internal/crypto/sig.js
index 27930ce1acf793..7e3b7aa7ff394d 100644
--- a/lib/internal/crypto/sig.js
+++ b/lib/internal/crypto/sig.js
@@ -9,7 +9,7 @@ const {
   ERR_INVALID_ARG_TYPE,
   ERR_INVALID_OPT_VALUE
 } = require('internal/errors').codes;
-const { validateString } = require('internal/validators');
+const { validateEncoding, validateString } = require('internal/validators');
 const {
   Sign: _Sign,
   Verify: _Verify,
@@ -50,8 +50,15 @@ Sign.prototype._write = function _write(chunk, encoding, callback) {
 
 Sign.prototype.update = function update(data, encoding) {
   encoding = encoding || getDefaultEncoding();
-  data = getArrayBufferView(data, 'data', encoding);
-  this[kHandle].update(data);
+
+  if (typeof data === 'string') {
+    validateEncoding(data, encoding);
+  } else if (!isArrayBufferView(data)) {
+    throw new ERR_INVALID_ARG_TYPE(
+      'data', ['string', 'Buffer', 'TypedArray', 'DataView'], data);
+  }
+
+  this[kHandle].update(data, encoding);
   return this;
 };
 
diff --git a/src/node_crypto.cc b/src/node_crypto.cc
index 1480eb04f8812d..3a1ff9de476a68 100644
--- a/src/node_crypto.cc
+++ b/src/node_crypto.cc
@@ -4509,12 +4509,25 @@ void Sign::SignInit(const FunctionCallbackInfo<Value>& args) {
 
 
 void Sign::SignUpdate(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+
   Sign* sign;
   ASSIGN_OR_RETURN_UNWRAP(&sign, args.Holder());
 
   Error err;
-  ArrayBufferViewContents<char> buf(args[0]);
-  err = sign->Update(buf.data(), buf.length());
+
+  // Only copy the data if we have to, because it's a string
+  if (args[0]->IsString()) {
+    StringBytes::InlineDecoder decoder;
+    enum encoding enc = ParseEncoding(env->isolate(), args[1], UTF8);
+
+    if (decoder.Decode(env, args[0].As<String>(), enc).IsNothing())
+      return;
+    err = sign->Update(decoder.out(), decoder.size());
+  } else {
+    ArrayBufferViewContents<char> buf(args[0]);
+    err = sign->Update(buf.data(), buf.length());
+  }
 
   sign->CheckThrow(err);
 }
@@ -4834,12 +4847,25 @@ void Verify::VerifyInit(const FunctionCallbackInfo<Value>& args) {
 
 
 void Verify::VerifyUpdate(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+
   Verify* verify;
   ASSIGN_OR_RETURN_UNWRAP(&verify, args.Holder());
 
   Error err;
-  ArrayBufferViewContents<char> buf(args[0]);
-  err = verify->Update(buf.data(), buf.length());
+
+  // Only copy the data if we have to, because it's a string
+  if (args[0]->IsString()) {
+    StringBytes::InlineDecoder decoder;
+    enum encoding enc = ParseEncoding(env->isolate(), args[1], UTF8);
+
+    if (decoder.Decode(env, args[0].As<String>(), enc).IsNothing())
+      return;
+    err = verify->Update(decoder.out(), decoder.size());
+  } else {
+    ArrayBufferViewContents<char> buf(args[0]);
+    err = verify->Update(buf.data(), buf.length());
+  }
 
   verify->CheckThrow(err);
 }