diff --git a/merge-stream/merge-stream-tests.ts b/merge-stream/merge-stream-tests.ts
new file mode 100644
index 0000000000..e0c744953e
--- /dev/null
+++ b/merge-stream/merge-stream-tests.ts
@@ -0,0 +1,13 @@
+/// <reference path="./merge-stream.d.ts" />
+
+import stream = require("stream");
+import Stream = stream.Readable;
+import merge = require("merge-stream");
+
+var stream1 = new Stream();
+var stream2 = new Stream();
+
+var merged = merge(stream1, stream2);
+
+var stream3 = new Stream();
+merged.add(stream3);
diff --git a/merge-stream/merge-stream.d.ts b/merge-stream/merge-stream.d.ts
new file mode 100644
index 0000000000..6dfffdb958
--- /dev/null
+++ b/merge-stream/merge-stream.d.ts
@@ -0,0 +1,16 @@
+// Type definitions for merge-stream
+// Project: https://github.com/grncdr/merge-stream
+// Definitions by: Keita Kagurazaka <https://github.com/k-kagurazaka>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+/// <reference path="../node/node.d.ts"/>
+
+declare module "merge-stream" {
+
+    interface IMergedStream extends NodeJS.ReadWriteStream {
+        add: (source: NodeJS.ReadableStream) => IMergedStream;
+    }
+
+    function merge<T extends NodeJS.ReadableStream>(...streams: T[]): IMergedStream;
+    export = merge;
+}