diff --git a/lib/src/generate/watch_impl.dart b/lib/src/generate/watch_impl.dart
index 6659dd0c2..42bea61f5 100644
--- a/lib/src/generate/watch_impl.dart
+++ b/lib/src/generate/watch_impl.dart
@@ -190,7 +190,7 @@ class WatchImpl {
 
   /// Checks if we should skip a watch event for this [id].
   bool _shouldSkipInput(AssetId id, ChangeType type) {
-    if (id.path.startsWith('.build')) return true;
+    if (id.path.contains('.build/')) return true;
     var node = _assetGraph.get(id);
     return node is GeneratedAssetNode && type != ChangeType.REMOVE;
   }
diff --git a/lib/src/package_graph/package_graph.dart b/lib/src/package_graph/package_graph.dart
index ddefc7638..711ef0fca 100644
--- a/lib/src/package_graph/package_graph.dart
+++ b/lib/src/package_graph/package_graph.dart
@@ -54,9 +54,13 @@ class PackageGraph {
     packagesFile.readAsLinesSync().skip(1).forEach((line) {
       var firstColon = line.indexOf(':');
       var name = line.substring(0, firstColon);
-      assert(line.endsWith('lib${Platform.pathSeparator}'));
+      assert(line.endsWith('lib/'));
       // Start after package_name:, and strip out trailing `lib` dir.
       var uriString = line.substring(firstColon + 1, line.length - 4);
+      // Strip the trailing slash, if present.
+      if (uriString.endsWith('/')) {
+        uriString = uriString.substring(0, uriString.length - 1);
+      }
       var uri;
       try {
         uri = Uri.parse(uriString);
diff --git a/test/asset/file_based_test.dart b/test/asset/file_based_test.dart
index 47c942261..78a4af468 100644
--- a/test/asset/file_based_test.dart
+++ b/test/asset/file_based_test.dart
@@ -4,13 +4,16 @@
 @TestOn('vm')
 import 'dart:io';
 
+import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
 import 'package:build/build.dart';
 
 import '../common/common.dart';
 
-final packageGraph = new PackageGraph.forPath('test/fixtures/basic_pkg');
+final packageGraph =
+    new PackageGraph.forPath('test/fixtures/basic_pkg');
+final newLine = Platform.isWindows ? '\r\n' :  '\n';
 
 main() {
   group('FileBasedAssetReader', () {
@@ -18,15 +21,15 @@ main() {
 
     test('can read any application package files', () async {
       expect(await reader.readAsString(makeAssetId('basic_pkg|hello.txt')),
-          'world\n');
+          'world$newLine');
       expect(await reader.readAsString(makeAssetId('basic_pkg|lib/hello.txt')),
-          'world\n');
+          'world$newLine');
       expect(await reader.readAsString(makeAssetId('basic_pkg|web/hello.txt')),
-          'world\n');
+          'world$newLine');
     });
 
     test('can read package dependency files in the lib dir', () async {
-      expect(await reader.readAsString(makeAssetId('a|lib/a.txt')), 'A\n');
+      expect(await reader.readAsString(makeAssetId('a|lib/a.txt')), 'A$newLine');
     });
 
     test('can check for existence of any application package files', () async {
@@ -101,7 +104,7 @@ main() {
       var asset = makeAsset('basic_pkg|test_file.txt', 'test');
       await writer.writeAsString(asset);
       var id = asset.id;
-      var file = new File('test/fixtures/${id.package}/${id.path}');
+      var file = new File(path.join('test', 'fixtures', id.package, id.path));
       expect(await file.exists(), isTrue);
       expect(await file.readAsString(), 'test');
 
diff --git a/test/generate/serve_test.dart b/test/generate/serve_test.dart
index 69e0e0b8e..288e19407 100644
--- a/test/generate/serve_test.dart
+++ b/test/generate/serve_test.dart
@@ -4,6 +4,7 @@
 import 'dart:async';
 
 import 'package:logging/logging.dart';
+import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
 import 'package:build/build.dart';
@@ -44,8 +45,8 @@ main() {
       checkOutputs({'a|web/a.txt.copy': 'a'}, result, writer.assets);
 
       await writer.writeAsString(makeAsset('a|web/a.txt', 'b'));
-      FakeWatcher
-          .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/a.txt'));
+      FakeWatcher.notifyWatchers(
+          new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'a.txt')));
 
       result = await nextResult(results);
       checkOutputs({'a|web/a.txt.copy': 'b',}, result, writer.assets);
@@ -82,8 +83,8 @@ main() {
       /// Make an edit to force another build, and we should block again.
       copyBuilder.blockUntil = buildBlocker2.future;
       await writer.writeAsString(makeAsset('a|web/a.txt', 'b'));
-      FakeWatcher
-          .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/a.txt'));
+      FakeWatcher.notifyWatchers(
+          new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'a.txt')));
       // Give the build enough time to get started.
       await wait(500);
       var done = new Completer();
diff --git a/test/generate/watch_test.dart b/test/generate/watch_test.dart
index 6d2a724ee..e82a6d67b 100644
--- a/test/generate/watch_test.dart
+++ b/test/generate/watch_test.dart
@@ -5,6 +5,7 @@ import 'dart:async';
 import 'dart:convert';
 
 import 'package:logging/logging.dart';
+import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 import 'package:watcher/watcher.dart';
 
@@ -40,8 +41,8 @@ main() {
         checkOutputs({'a|web/a.txt.copy': 'a',}, result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/a.txt', 'b'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/a.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'a.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/a.txt.copy': 'b',}, result, writer.assets);
@@ -57,8 +58,8 @@ main() {
         checkOutputs({'a|web/a.txt.copy': 'a',}, result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/b.txt', 'b'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.ADD, 'a/web/b.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.ADD, path.join('a', 'web', 'b.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/b.txt.copy': 'b',}, result, writer.assets);
@@ -78,8 +79,8 @@ main() {
             result, writer.assets);
 
         await writer.delete(makeAssetId('a|web/a.txt'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.REMOVE, 'a/web/a.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.REMOVE, path.join('a', 'web', 'a.txt')));
 
         result = await nextResult(results);
 
@@ -104,11 +105,11 @@ main() {
             result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/c.txt', 'c'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.ADD, 'a/web/c.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.ADD, path.join('a', 'web', 'c.txt')));
         await writer.delete(makeAssetId('a|web/a.txt'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.REMOVE, 'a/web/a.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.REMOVE, path.join('a', 'web', 'a.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/c.txt.copy': 'c'}, result, writer.assets);
@@ -141,8 +142,8 @@ main() {
         await writer.writeAsString(makeAsset('test|lib/test.dart', ''),
             lastModified: new DateTime.now().add(new Duration(days: 1)));
         await writer.writeAsString(makeAsset('a|web/a.txt', 'b'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/a.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'a.txt')));
 
         result = await nextResult(results);
         expect(result.status, BuildStatus.Failure);
@@ -165,8 +166,8 @@ main() {
             result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/a.txt', 'b'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/a.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'a.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/a.txt.copy': 'b', 'a|web/a.txt.copy.copy': 'b'},
@@ -188,8 +189,8 @@ main() {
             result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/b.txt', 'b'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.ADD, 'a/web/b.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.ADD, path.join('a', 'web', 'b.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/b.txt.copy': 'b', 'a|web/b.txt.copy.copy': 'b'},
@@ -219,8 +220,8 @@ main() {
         }, result, writer.assets);
 
         await writer.delete(makeAssetId('a|web/a.txt'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.REMOVE, 'a/web/a.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.REMOVE, path.join('a', 'web', 'a.txt')));
 
         result = await nextResult(results);
         // Shouldn't rebuild anything, no outputs.
@@ -249,8 +250,8 @@ main() {
             result, writer.assets);
 
         await writer.delete(makeAssetId('a|web/a.txt.copy'));
-        FakeWatcher.notifyWatchers(
-            new WatchEvent(ChangeType.REMOVE, 'a/web/a.txt.copy'));
+        FakeWatcher.notifyWatchers(new WatchEvent(
+            ChangeType.REMOVE, path.join('a', 'web', 'a.txt.copy')));
 
         result = await nextResult(results);
         // Should rebuild the generated asset and its outputs.
@@ -275,8 +276,8 @@ main() {
         checkOutputs({'a|web/a.txt.copy': 'b'}, result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/b.txt', 'c'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/b.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'b.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/a.txt.copy': 'c'}, result, writer.assets);
@@ -303,8 +304,8 @@ main() {
             result, writer.assets);
 
         await writer.writeAsString(makeAsset('a|web/b.txt', 'c'));
-        FakeWatcher
-            .notifyWatchers(new WatchEvent(ChangeType.MODIFY, 'a/web/b.txt'));
+        FakeWatcher.notifyWatchers(
+            new WatchEvent(ChangeType.MODIFY, path.join('a', 'web', 'b.txt')));
 
         result = await nextResult(results);
         checkOutputs({'a|web/a.txt.copy.copy': 'c'}, result, writer.assets);
diff --git a/test/package_graph/package_graph_test.dart b/test/package_graph/package_graph_test.dart
index 04e697e6b..caeaa71f8 100644
--- a/test/package_graph/package_graph_test.dart
+++ b/test/package_graph/package_graph_test.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 @TestOn('vm')
+import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
 import 'package:build/build.dart';
@@ -44,17 +45,17 @@ main() {
 
       test('pub dependency', () {
         expectPkg(graph['a'], 'a', '2.0.0', PackageDependencyType.Pub,
-            '$basicPkgPath/pkg/a/', [graph['b'], graph['c']]);
+            '$basicPkgPath/pkg/a', [graph['b'], graph['c']]);
       });
 
       test('git dependency', () {
         expectPkg(graph['b'], 'b', '3.0.0', PackageDependencyType.Github,
-            '$basicPkgPath/pkg/b/', [graph['c']]);
+            '$basicPkgPath/pkg/b', [graph['c']]);
       });
 
       test('path dependency', () {
         expectPkg(graph['c'], 'c', '4.0.0', PackageDependencyType.Path,
-            '$basicPkgPath/pkg/c/', [graph['basic_pkg']]);
+            '$basicPkgPath/pkg/c', [graph['basic_pkg']]);
       });
     });
 
@@ -87,10 +88,10 @@ main() {
 
         // Package `c` does not appear because this is not the root package.
         expectPkg(graph['a'], 'a', '2.0.0', PackageDependencyType.Pub,
-            '$withDevDepsPkgPath/pkg/a/', []);
+            '$withDevDepsPkgPath/pkg/a', []);
 
         expectPkg(graph['b'], 'b', '3.0.0', PackageDependencyType.Pub,
-            '$withDevDepsPkgPath/pkg/b/', []);
+            '$withDevDepsPkgPath/pkg/b', []);
 
         expect(graph['c'], isNull);
       });
@@ -110,11 +111,15 @@ main() {
 
     test('missing pubspec throws on create', () {
       expect(
-          () => new PackageGraph.forPath('test/fixtures/no_pubspec'), throws);
+          () => new PackageGraph.forPath(
+              path.join('test', 'fixtures', 'no_pubspec')),
+          throws);
     });
 
     test('missing .packages file throws on create', () {
-      expect(() => new PackageGraph.forPath('test/fixtures/no_packages_file'),
+      expect(
+          () => new PackageGraph.forPath(
+              path.join('test', 'fixtures', 'no_packages_file')),
           throws);
     });
   });