diff --git a/tslib.es6.js b/tslib.es6.js
index 7be1c94..55dd360 100644
--- a/tslib.es6.js
+++ b/tslib.es6.js
@@ -228,8 +228,9 @@ export function __await(v) {
 export function __asyncGenerator(thisArg, _arguments, generator) {
     if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
     var g = generator.apply(thisArg, _arguments || []), i, q = [];
-    return i = {}, verb("next"), verb("throw"), verb("return"), i[Symbol.asyncIterator] = function () { return this; }, i;
-    function verb(n) { if (g[n]) i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; }
+    return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+    function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
+    function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
     function step(r) { r.value instanceof __await ? Promise.resolve(r.value.v).then(fulfill, reject) : settle(q[0][2], r); }
     function fulfill(value) { resume("next", value); }
diff --git a/tslib.es6.mjs b/tslib.es6.mjs
index c8e2999..65081a6 100644
--- a/tslib.es6.mjs
+++ b/tslib.es6.mjs
@@ -228,8 +228,9 @@ export function __await(v) {
 export function __asyncGenerator(thisArg, _arguments, generator) {
   if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
   var g = generator.apply(thisArg, _arguments || []), i, q = [];
-  return i = {}, verb("next"), verb("throw"), verb("return"), i[Symbol.asyncIterator] = function () { return this; }, i;
-  function verb(n) { if (g[n]) i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; }
+  return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+  function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
+  function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
   function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
   function step(r) { r.value instanceof __await ? Promise.resolve(r.value.v).then(fulfill, reject) : settle(q[0][2], r); }
   function fulfill(value) { resume("next", value); }
diff --git a/tslib.js b/tslib.js
index 343ecde..697469f 100644
--- a/tslib.js
+++ b/tslib.js
@@ -276,10 +276,11 @@ var __disposeResources;
     __asyncGenerator = function (thisArg, _arguments, generator) {
         if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
         var g = generator.apply(thisArg, _arguments || []), i, q = [];
-        return i = {}, verb("next"), verb("throw"), verb("return"), i[Symbol.asyncIterator] = function () { return this; }, i;
-        function verb(n) { if (g[n]) i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; }
+        return i = {}, verb("next"), verb("throw"), verb("return", awaitReturn), i[Symbol.asyncIterator] = function () { return this; }, i;
+        function awaitReturn(f) { return function (v) { return Promise.resolve(v).then(f, reject); }; }
+        function verb(n, f) { if (g[n]) { i[n] = function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]) > 1 || resume(n, v); }); }; if (f) i[n] = f(i[n]); } }
         function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(q[0][3], e); } }
-        function step(r) { r.value instanceof __await ? Promise.resolve(r.value.v).then(fulfill, reject) : settle(q[0][2], r);  }
+        function step(r) { r.value instanceof __await ? Promise.resolve(r.value.v).then(fulfill, reject) : settle(q[0][2], r); }
         function fulfill(value) { resume("next", value); }
         function reject(value) { resume("throw", value); }
         function settle(f, v) { if (f(v), q.shift(), q.length) resume(q[0][0], q[0][1]); }