diff --git a/lib/internal/process/promises.js b/lib/internal/process/promises.js
index 22f1959784be9a..563517c94e2936 100644
--- a/lib/internal/process/promises.js
+++ b/lib/internal/process/promises.js
@@ -2,7 +2,9 @@
 
 const promiseRejectEvent = process._promiseRejectEvent;
 const hasBeenNotifiedProperty = new WeakMap();
+const promiseToGuidProperty = new WeakMap();
 const pendingUnhandledRejections = [];
+let lastPromiseId = 1;
 
 exports.setup = setupPromises;
 
@@ -18,6 +20,7 @@ function setupPromises(scheduleMicrotasks) {
 
   function unhandledRejection(promise, reason) {
     hasBeenNotifiedProperty.set(promise, false);
+    promiseToGuidProperty.set(promise, lastPromiseId++);
     addPendingUnhandledRejection(promise, reason);
   }
 
@@ -25,9 +28,15 @@ function setupPromises(scheduleMicrotasks) {
     var hasBeenNotified = hasBeenNotifiedProperty.get(promise);
     if (hasBeenNotified !== undefined) {
       hasBeenNotifiedProperty.delete(promise);
+      const uid = promiseToGuidProperty.get(promise);
+      promiseToGuidProperty.delete(promise);
       if (hasBeenNotified === true) {
         process.nextTick(function() {
-          process.emit('rejectionHandled', promise);
+          if(!process.emit('rejectionHandled', promise)) {
+            process.emitWarning('Promise Rejection Handled Asynchronously'
+                              + '(rejection id: ' + uid +') ',
+                              'PromiseRejectionHandledWarning');
+          }
         });
       }
 
@@ -35,15 +44,18 @@ function setupPromises(scheduleMicrotasks) {
   }
 
   function emitPendingUnhandledRejections() {
-    var hadListeners = false;
+    let hadListeners = false;
     while (pendingUnhandledRejections.length > 0) {
-      var promise = pendingUnhandledRejections.shift();
-      var reason = pendingUnhandledRejections.shift();
+      const promise = pendingUnhandledRejections.shift();
+      const reason = pendingUnhandledRejections.shift();
       if (hasBeenNotifiedProperty.get(promise) === false) {
         hasBeenNotifiedProperty.set(promise, true);
+        const uid = promiseToGuidProperty.get(promise);
         if (!process.emit('unhandledRejection', reason, promise)) {
-          // Nobody is listening.
-          // TODO(petkaantonov) Take some default action, see #830
+          process.emitWarning('Possibly unhandled promise rejection ' 
+                              + '(rejection id: ' + uid +'): '
+                              + reason,
+                              'UnhandledPromiseRejectionWarning');
         } else {
           hadListeners = true;
         }