diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 90c5ee9d7797ca..dccd6faeef5330 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -827,9 +827,9 @@ void IndexOfString(const FunctionCallbackInfo<Value>& args) {
   Local<String> needle = args[1].As<String>();
   const char* haystack = ts_obj_data;
   const size_t haystack_length = ts_obj_length;
-  // Extended latin-1 characters are 2 bytes in Utf8.
+
   const size_t needle_length =
-      enc == BINARY ? needle->Length() : needle->Utf8Length();
+      StringBytes::Size(args.GetIsolate(), needle, enc);
 
 
   if (needle_length == 0 || haystack_length == 0) {
diff --git a/test/parallel/test-buffer-indexof.js b/test/parallel/test-buffer-indexof.js
index 999d6590a9c69d..b085b4b1ea66ff 100644
--- a/test/parallel/test-buffer-indexof.js
+++ b/test/parallel/test-buffer-indexof.js
@@ -233,6 +233,12 @@ var allCharsBufferUcs2 = new Buffer(allCharsString, 'ucs2');
 assert.equal(-1, allCharsBufferUtf8.indexOf('notfound'));
 assert.equal(-1, allCharsBufferUcs2.indexOf('notfound'));
 
+// Needle is longer than haystack, but only because it's encoded as UTF-16
+assert.strictEqual(new Buffer('aaaa').indexOf('a'.repeat(4), 'ucs2'), -1);
+
+assert.strictEqual(new Buffer('aaaa').indexOf('a'.repeat(4), 'utf8'), 0);
+assert.strictEqual(new Buffer('aaaa').indexOf('你好', 'ucs2'), -1);
+
 {
   // Find substrings in Utf8.
   const lengths = [1, 3, 15];  // Single char, simple and complex.