diff --git a/reporting/bufferSize.html b/reporting/bufferSize.html
index b3512b3bc93b32..0e50526772e221 100644
--- a/reporting/bufferSize.html
+++ b/reporting/bufferSize.html
@@ -8,22 +8,20 @@
 <script src="/resources/testdriver-vendor.js"></script>
 <script>
   // Test the buffer size (100) of ReportingObserver.
-  async_test(async function(test) {
-    for (i = 0; i != 110; ++i)
+  promise_test(async function(test) {
+    for (let i = 0; i != 110; ++i)
       await test_driver.generate_test_report("" + i);
 
-    var observer = new ReportingObserver(function(reports) {
-      test.step(function() {
-        // Only (the most recent) 100 reports should be observed, even though
-        // 110 were buffered.
-        assert_equals(reports.length, 100);
-        for(i = 0; i != 100; ++i) {
-          assert_equals(reports[i].body.message, "" + (i + 10));
-        }
-      });
+    let reports = await new Promise(resolve => {
+      let observer = new ReportingObserver(resolve, {buffered:true});
+      observer.observe();
+    });
 
-      test.done();
-    }, {buffered: true});
-    observer.observe();
+    // Only (the most recent) 100 reports should be observed, even though
+    // 110 were buffered.
+    assert_equals(reports.length, 100);
+    for (let i = 0; i != 100; ++i) {
+      assert_equals(reports[i].body.message, "" + (i + 10));
+    }
   }, "Buffer size");
 </script>
diff --git a/reporting/disconnect.html b/reporting/disconnect.html
index 2dc5e8fd2de724..12d33db8ff2925 100644
--- a/reporting/disconnect.html
+++ b/reporting/disconnect.html
@@ -7,19 +7,20 @@
 <script src="/resources/testdriver.js"></script>
 <script src="/resources/testdriver-vendor.js"></script>
 <script>
-  async_test(async function(test) {
-    var observer = new ReportingObserver(function(reports, observer) {
-      test.step(function() {
-        assert_equals(reports.length, 1);
-        assert_equals(reports[0].body.message, "Test message.");
-      });
-      test.done();
+promise_test(async test => {
+    let observer;
+    const reportsPromise = new Promise(resolve => {
+      observer = new ReportingObserver(resolve);
+      observer.observe();
     });
-    observer.observe();
 
     // The observer should still receive this report even though disconnect()
     // is called immediately afterwards.
-    await test_driver.generate_test_report("Test message.");
-    observer.disconnect();
+    await test_driver.generate_test_report("Test message.")
+        .then(() => { observer.disconnect(); });
+
+    const reports = await reportsPromise;
+    assert_equals(reports.length, 1);
+    assert_equals(reports[0].body.message, "Test message.");
   }, "Disconnect");
 </script>
diff --git a/reporting/path-absolute-endpoint.https.sub.html b/reporting/path-absolute-endpoint.https.sub.html
index 144fcb024e3917..6abc5ee5a32800 100644
--- a/reporting/path-absolute-endpoint.https.sub.html
+++ b/reporting/path-absolute-endpoint.https.sub.html
@@ -38,7 +38,7 @@
           assert_equals(reports[0].body.sample, "");
           assert_equals(reports[0].body.disposition, "enforce");
           assert_equals(reports[0].body.statusCode, 0);
-          assert_equals(reports[0].body.lineNumber, 66);
+          assert_equals(reports[0].body.lineNumber, 61);
           assert_equals(reports[0].body.columnNumber, 0);
         });
 
@@ -51,17 +51,12 @@
     onload='t.unreached_func("The image should not have loaded");'
     onerror='t.done();'>
   <script>
-    async_test(async (t) => {
-      try {
-        const endpoint = `${base_url}/reporting/resources/report.py`;
-        const id = 'd0d517bf-891b-457a-b970-8b2b2c81a0bf';
-        await wait(3000);
-        const reports = await pollReports(endpoint, id);
-        checkReportExists(reports, 'csp-violation', location.href);
-        t.done();
-      } catch (e) {
-        t.step(() => { throw e; });
-      }
+    promise_test(async t => {
+      const endpoint = `${base_url}/reporting/resources/report.py`;
+      const id = 'd0d517bf-891b-457a-b970-8b2b2c81a0bf';
+      await wait(3000);
+      const reports = await pollReports(endpoint, id);
+      checkReportExists(reports, 'csp-violation', location.href);
     }, "Reporting endpoints received reports.");
   </script>