diff --git a/pkgs/test/CHANGELOG.md b/pkgs/test/CHANGELOG.md
index 3afab02..4be8718 100644
--- a/pkgs/test/CHANGELOG.md
+++ b/pkgs/test/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 1.16.0-nullsafety.11
+
+* Set up a stack trace mapper in precompiled mode if source maps exist. If
+  the stack traces are already mapped then this has no effect, otherwise it
+  will try to map any JS lines it sees.
+
 ## 1.16.0-nullsafety.10
 
 * Allow injecting a test channel for browser tests.
diff --git a/pkgs/test/lib/src/runner/browser/platform.dart b/pkgs/test/lib/src/runner/browser/platform.dart
index d0e88a0..1af5dab 100644
--- a/pkgs/test/lib/src/runner/browser/platform.dart
+++ b/pkgs/test/lib/src/runner/browser/platform.dart
@@ -259,6 +259,8 @@
       if (browser.isJS) {
         if (suiteConfig.precompiledPath == null) {
           await _compileSuite(path, suiteConfig);
+        } else {
+          await _addPrecompiledStackTraceMapper(path, suiteConfig);
         }
       }
 
@@ -410,6 +412,20 @@
     });
   }
 
+  Future<void> _addPrecompiledStackTraceMapper(
+      String dartPath, SuiteConfiguration suiteConfig) async {
+    if (suiteConfig.jsTrace) return;
+    var mapPath = p.join(
+        suiteConfig.precompiledPath, dartPath + '.browser_test.dart.js.map');
+    var mapFile = File(mapPath);
+    if (mapFile.existsSync()) {
+      _mappers[dartPath] = JSStackTraceMapper(mapFile.readAsStringSync(),
+          mapUrl: p.toUri(mapPath),
+          sdkRoot: Uri.parse(r'/packages/$sdk'),
+          packageMap: (await currentPackageConfig).toPackageMap());
+    }
+  }
+
   /// Returns the [BrowserManager] for [runtime], which should be a browser.
   ///
   /// If no browser manager is running yet, starts one.
diff --git a/pkgs/test/pubspec.yaml b/pkgs/test/pubspec.yaml
index b182206..5d35fb7 100644
--- a/pkgs/test/pubspec.yaml
+++ b/pkgs/test/pubspec.yaml
@@ -1,5 +1,5 @@
 name: test
-version: 1.16.0-nullsafety.10
+version: 1.16.0-nullsafety.11
 description: A full featured library for writing and running Dart tests.
 homepage: https://github.com/dart-lang/test/blob/master/pkgs/test