diff --git a/vendor/google.golang.org/protobuf/runtime/protoiface/legacy.go b/vendor/google.golang.org/protobuf/runtime/protoiface/legacy.go
new file mode 100644
index 0000000..c587276
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/runtime/protoiface/legacy.go
@@ -0,0 +1,15 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package protoiface
+
+type MessageV1 interface {
+	Reset()
+	String() string
+	ProtoMessage()
+}
+
+type ExtensionRangeV1 struct {
+	Start, End int32 // both inclusive
+}