diff --git a/stored-credentials/README.md b/stored-credentials/README.md
index b9d70f7a..f62758a8 100644
--- a/stored-credentials/README.md
+++ b/stored-credentials/README.md
@@ -3,30 +3,35 @@
 **Although this add-on uses a stored password to authenticate to a web server,
 it should not be taken as an example of how to store or work securely with
 passwords. It's only a demonstration of how to use the
-[`webRequest.onAuthRequired`](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/webRequest/onAuthRequired) API.**
+[`webRequest.onAuthRequired`](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/webRequest/onAuthRequired)
+API.**
 
-This add-on uses the [`webRequest.onAuthRequired`](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/webRequest/onAuthRequired) API to log the user into
-the demo site at https://httpbin.org/basic-auth/user/passwd using a stored
-username and password.
+This add-on uses the
+[`webRequest.onAuthRequired`](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/webRequest/onAuthRequired)
+API to log the user into the demo site at
+https://httpbin.org/basic-auth/user/passwd using a stored username and password.
 
-This add-on stores a username and password using the [`storage.local`](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/storage/local) API.
-The default value is the correct value
-for the demo site:
+This add-on stores a username and password using the
+[`storage.local`](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/storage/local)
+API. The default value is the correct value for the demo site:
 
     username: "user"
     password: "passwd"
 
-You can change the default values in the add-on's [options page](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Options_pages).
+You can change the default values in the add-on's [options
+page](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Options_pages).
 
 The add-on then uses `webRequest.onAuthRequired` to intercept authentication
-requests from the demo site. When it gets
-such a request, it fetches the stored credentials and supplies them
-asynchronously.
+requests from the demo site. When it gets such a request, it fetches the stored
+credentials and supplies them asynchronously.
 
 To try out the add-on:
 
-* Before installing the add-on, visit https://httpbin.org/basic-auth/user/passwd,
-and see that it asks for a username and password.
-* [Install the add-on](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Temporary_Installation_in_Firefox) in Firefox 54 or later.
-* Visit https://httpbin.org/basic-auth/user/passwd again, and see that authentication succeeds automatically.
- 
+* Before installing the add-on, visit
+  https://httpbin.org/basic-auth/user/passwd, and see that it asks for a
+  username and password.
+* [Install the
+  add-on](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Temporary_Installation_in_Firefox)
+  in Firefox 54 or later.
+* Visit https://httpbin.org/basic-auth/user/passwd again, and see that
+  authentication succeeds automatically.
diff --git a/stored-credentials/auth.js b/stored-credentials/auth.js
index e4ffda1d..d7168ef3 100644
--- a/stored-credentials/auth.js
+++ b/stored-credentials/auth.js
@@ -1,6 +1,4 @@
-
 let target = "https://httpbin.org/basic-auth/*";
-
 let pendingRequests = [];
 
 /*
@@ -14,27 +12,26 @@ function completed(requestDetails) {
   }
 }
 
-function provideCredentialsAsync(requestDetails) {
-  // If we have seen this request before,
-  // then assume our credentials were bad,
+async function provideCredentialsAsync(requestDetails, asyncCallback) {
+  // If we have seen this request before, then assume our credentials were bad,
   // and give up.
   if (pendingRequests.indexOf(requestDetails.requestId) != -1) {
     console.log("bad credentials for: " + requestDetails.requestId);
     return {cancel: true};
-    
   } else {
     pendingRequests.push(requestDetails.requestId);
     console.log("providing credentials for: " + requestDetails.requestId);
-    // we can return a promise that will be resolved
-    // with the stored credentials
-    return browser.storage.local.get(null);
+    // We can respond asynchronously by calling asyncCallback and providing the
+    // authentication credentials.
+    const {authCredentials} = await browser.storage.local.get("authCredentials");
+    asyncCallback({authCredentials});
   }
 }
 
 browser.webRequest.onAuthRequired.addListener(
     provideCredentialsAsync,
     {urls: [target]},
-    ["blocking"]
+    ["asyncBlocking"]
   );
 
 browser.webRequest.onCompleted.addListener(
diff --git a/stored-credentials/manifest.json b/stored-credentials/manifest.json
index 65a15c8e..5650e235 100644
--- a/stored-credentials/manifest.json
+++ b/stored-credentials/manifest.json
@@ -25,6 +25,7 @@
   "permissions": [
     "webRequest",
     "webRequestBlocking",
+    "webRequestAuthProvider",
     "storage",
     "https://httpbin.org/basic-auth/*"
   ]