diff --git a/types/defined/defined-tests.ts b/types/defined/defined-tests.ts
new file mode 100644
index 0000000000..5a9d055114
--- /dev/null
+++ b/types/defined/defined-tests.ts
@@ -0,0 +1,7 @@
+import defined = require('defined');
+
+const opts = { x: undefined, y : false, w : 4 };
+// $ExpectType number | boolean | undefined
+defined<boolean | number | undefined>(opts.x, opts.y, opts.w, 100);
+// $ExpectType any
+defined(opts.x, opts.y, opts.w, 100);
diff --git a/types/defined/index.d.ts b/types/defined/index.d.ts
new file mode 100644
index 0000000000..1e7f4afc6a
--- /dev/null
+++ b/types/defined/index.d.ts
@@ -0,0 +1,9 @@
+// Type definitions for defined 1.0
+// Project: https://github.com/substack/defined
+// Definitions by: BendingBender <https://github.com/BendingBender>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+export = defined;
+
+declare function defined<T>(...args: T[]): T;
+declare function defined(...args: any[]): any;
diff --git a/types/defined/tsconfig.json b/types/defined/tsconfig.json
new file mode 100644
index 0000000000..63c6202b4c
--- /dev/null
+++ b/types/defined/tsconfig.json
@@ -0,0 +1,22 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "defined-tests.ts"
+    ]
+}
diff --git a/types/defined/tslint.json b/types/defined/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/defined/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }