diff --git a/promise/.eslintrc.json b/promise/.eslintrc.json
new file mode 100644
index 0000000..95a6242
--- /dev/null
+++ b/promise/.eslintrc.json
@@ -0,0 +1,3 @@
+{
+	"globals": { "Promise": true }
+}
diff --git a/promise/sleep.js b/promise/sleep.js
new file mode 100644
index 0000000..5e5c07a
--- /dev/null
+++ b/promise/sleep.js
@@ -0,0 +1,21 @@
+"use strict";
+
+var isValue       = require("es5-ext/object/is-value")
+  , isPromise     = require("es5-ext/object/is-promise")
+  , nextTick      = require("next-tick")
+  , ensureTimeout = require("../valid-timeout");
+
+module.exports = function (/* timeout */) {
+	var Constructor = isPromise(this) ? this.constructor : Promise;
+	var timeout = arguments[0];
+	if (isValue(timeout)) timeout = ensureTimeout(timeout);
+	return new Constructor(function (resolve) {
+		if (isValue(timeout)) {
+			setTimeout(function () {
+				resolve();
+			}, timeout);
+		} else {
+			nextTick(resolve);
+		}
+	});
+};
diff --git a/test/promise/sleep.js b/test/promise/sleep.js
new file mode 100644
index 0000000..1c7e796
--- /dev/null
+++ b/test/promise/sleep.js
@@ -0,0 +1,34 @@
+"use strict";
+
+var delay = require("../../delay");
+
+module.exports = function (t, a) {
+	if (typeof Promise !== "function") return null;
+	return {
+		Tick: function (d) {
+			var isInvoked = false;
+			t().then(function (result) {
+				isInvoked = true;
+				delay(function () {
+					a(result, undefined);
+					d();
+				})();
+			}, delay(d));
+			a(isInvoked, false);
+		},
+		Timeout: function (d) {
+			var isInvoked = false;
+			t(100).then(
+				delay(function (result) {
+					isInvoked = true;
+					a(result, undefined);
+					d();
+				}),
+				delay(d)
+			);
+			setTimeout(function () {
+				a(isInvoked, false);
+			}, 50);
+		}
+	};
+};