diff --git a/lib/buffer.js b/lib/buffer.js
index 6514d0eb6dcf5d..881bdc2e1183d1 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -477,10 +477,14 @@ function slowIndexOf(buffer, val, byteOffset, encoding) {
 }
 
 Buffer.prototype.indexOf = function indexOf(val, byteOffset, encoding) {
-  if (byteOffset > 0x7fffffff)
+  if (typeof byteOffset === 'string') {
+    encoding = byteOffset;
+    byteOffset = 0;
+  } else if (byteOffset > 0x7fffffff) {
     byteOffset = 0x7fffffff;
-  else if (byteOffset < -0x80000000)
+  } else if (byteOffset < -0x80000000) {
     byteOffset = -0x80000000;
+  }
   byteOffset >>= 0;
 
   if (typeof val === 'string') {
diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index dca75a817b7414..988e41dbc9aa22 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -849,7 +849,9 @@ 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;
-  const size_t needle_length = needle->Utf8Length();
+  // Extended latin-1 characters are 2 bytes in Utf8.
+  const size_t needle_length =
+      enc == BINARY ? needle->Length() : needle->Utf8Length();
 
 
   if (needle_length == 0 || haystack_length == 0) {
diff --git a/test/parallel/test-buffer-indexof.js b/test/parallel/test-buffer-indexof.js
index aac5b18f718cb3..b075c3a10d8f4c 100644
--- a/test/parallel/test-buffer-indexof.js
+++ b/test/parallel/test-buffer-indexof.js
@@ -109,6 +109,20 @@ assert.equal(
 assert.equal(
     Buffer(b.toString('binary'), 'binary')
     .indexOf(Buffer('d', 'binary'), 0, 'binary'), 3);
+assert.equal(
+    Buffer('aa\u00e8aa', 'binary')
+    .indexOf('\u00e8', 'binary'), 2);
+assert.equal(
+    Buffer('\u00e8', 'binary')
+    .indexOf('\u00e8', 'binary'), 0);
+assert.equal(
+    Buffer('\u00e8', 'binary')
+    .indexOf(Buffer('\u00e8', 'binary'), 'binary'), 0);
+
+
+// test optional offset with passed encoding
+assert.equal(new Buffer('aaaa0').indexOf('30', 'hex'), 4);
+assert.equal(new Buffer('aaaa00a').indexOf('3030', 'hex'), 4);
 
 
 // test usc2 encoding