diff --git a/empower/empower-tests.ts b/empower/empower-tests.ts
new file mode 100644
index 0000000000..3a5cbe1504
--- /dev/null
+++ b/empower/empower-tests.ts
@@ -0,0 +1,17 @@
+/// <reference path="./empower.d.ts" />
+
+var baseAssert: any;
+var fakeFormatter: any;
+
+()=> {
+    var assert = empower(baseAssert, fakeFormatter);
+};
+
+var option: empower.Options = {
+    modifyMessageOnRethrow: false,
+    saveContextOnRethrow: false
+};
+
+()=> {
+    var assert = empower(baseAssert, fakeFormatter, option);
+};
diff --git a/empower/empower.d.ts b/empower/empower.d.ts
new file mode 100644
index 0000000000..02b34cbcaa
--- /dev/null
+++ b/empower/empower.d.ts
@@ -0,0 +1,19 @@
+// Type definitions for empower
+// Project: https://github.com/twada/empower
+// Definitions by: vvakame <https://github.com/vvakame>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+declare function empower(originalAssert: any, formatter: any, options?: empower.Options): any;
+
+declare module empower {
+    export interface Options {
+        destructive?: boolean;
+        modifyMessageOnRethrow?: boolean;
+        saveContextOnRethrow?: boolean;
+        patterns?: string[];
+    }
+}
+
+declare module "empower" {
+    export = empower;
+}