diff --git a/pkgs/watcher/lib/src/directory_watcher/polling.dart b/pkgs/watcher/lib/src/directory_watcher/polling.dart
index 684f7aa..12a3245 100644
--- a/pkgs/watcher/lib/src/directory_watcher/polling.dart
+++ b/pkgs/watcher/lib/src/directory_watcher/polling.dart
@@ -7,7 +7,6 @@
 import 'dart:async';
 import 'dart:io';
 
-import 'package:crypto/crypto.dart';
 import 'package:stack_trace/stack_trace.dart';
 
 import '../async_queue.dart';
@@ -46,10 +45,10 @@
   /// directory contents.
   final Duration _pollingDelay;
 
-  /// The previous status of the files in the directory.
+  /// The previous modification times of the files in the directory.
   ///
   /// Used to tell which files have been modified.
-  final _statuses = new Map<String, _FileStatus>();
+  final _lastModifieds = new Map<String, DateTime>();
 
   /// The subscription used while [directory] is being listed.
   ///
@@ -89,7 +88,7 @@
     // Don't process any remaining files.
     _filesToProcess.clear();
     _polledFiles.clear();
-    _statuses.clear();
+    _lastModifieds.clear();
   }
 
   /// Scans the contents of the directory once to see which files have been
@@ -135,32 +134,25 @@
     return getModificationTime(file).then((modified) {
       if (_events.isClosed) return null;
 
-      var lastStatus = _statuses[file];
+      var lastModified = _lastModifieds[file];
 
       // If its modification time hasn't changed, assume the file is unchanged.
-      if (lastStatus != null && lastStatus.modified == modified) {
+      if (lastModified != null && lastModified == modified) {
         // The file is still here.
         _polledFiles.add(file);
         return null;
       }
 
-      return _hashFile(file).then((hash) {
-        if (_events.isClosed) return;
+      if (_events.isClosed) return null;
 
-        var status = new _FileStatus(modified, hash);
-        _statuses[file] = status;
-        _polledFiles.add(file);
+      _lastModifieds[file] = modified;
+      _polledFiles.add(file);
 
-        // Only notify if we're ready to emit events.
-        if (!isReady) return;
+      // Only notify if we're ready to emit events.
+      if (!isReady) return null;
 
-        // And the file is different.
-        var changed = lastStatus == null || !_sameHash(lastStatus.hash, hash);
-        if (!changed) return;
-
-        var type = lastStatus == null ? ChangeType.ADD : ChangeType.MODIFY;
-        _events.add(new WatchEvent(type, file));
-      });
+      var type = lastModified == null ? ChangeType.ADD : ChangeType.MODIFY;
+      _events.add(new WatchEvent(type, file));
     });
   }
 
@@ -169,10 +161,10 @@
   Future _completePoll() {
     // Any files that were not seen in the last poll but that we have a
     // status for must have been removed.
-    var removedFiles = _statuses.keys.toSet().difference(_polledFiles);
+    var removedFiles = _lastModifieds.keys.toSet().difference(_polledFiles);
     for (var removed in removedFiles) {
       if (isReady) _events.add(new WatchEvent(ChangeType.REMOVE, removed));
-      _statuses.remove(removed);
+      _lastModifieds.remove(removed);
     }
 
     if (!isReady) _ready.complete();
@@ -183,37 +175,4 @@
       _poll();
     });
   }
-
-  /// Calculates the SHA-1 hash of the file at [path].
-  Future<List<int>> _hashFile(String path) {
-    return Chain.track(new File(path).readAsBytes()).then((bytes) {
-      var sha1 = new SHA1();
-      sha1.add(bytes);
-      return sha1.close();
-    });
-  }
-
-  /// Returns `true` if [a] and [b] are the same hash value, i.e. the same
-  /// series of byte values.
-  bool _sameHash(List<int> a, List<int> b) {
-    // Hashes should always be the same size.
-    assert(a.length == b.length);
-
-    for (var i = 0; i < a.length; i++) {
-      if (a[i] != b[i]) return false;
-    }
-
-    return true;
-  }
 }
-
-class _FileStatus {
-  /// The last time the file was modified.
-  DateTime modified;
-
-  /// The SHA-1 hash of the contents of the file.
-  List<int> hash;
-
-  _FileStatus(this.modified, this.hash);
-}
-
diff --git a/pkgs/watcher/pubspec.yaml b/pkgs/watcher/pubspec.yaml
index a967294..c77dddf 100644
--- a/pkgs/watcher/pubspec.yaml
+++ b/pkgs/watcher/pubspec.yaml
@@ -1,13 +1,11 @@
 name: watcher
-version: 0.9.2
+version: 0.9.3-dev
 author: "Dart Team <misc@dartlang.org>"
 homepage: http://www.dartlang.org
 description: >
-  A file watcher. It monitors (currently by polling) for changes to contents
-  of directories and notifies you when files have been added, removed, or
-  modified.
+  A file watcher. It monitors for changes to contents of directories and
+  notifies you when files have been added, removed, or modified.
 dependencies:
-  crypto: ">=0.9.0 <0.10.0"
   path: ">=0.9.0 <2.0.0"
   stack_trace: ">=0.9.1 <0.10.0"
 dev_dependencies:
diff --git a/pkgs/watcher/test/directory_watcher/linux_test.dart b/pkgs/watcher/test/directory_watcher/linux_test.dart
index f53b272..c2d0176 100644
--- a/pkgs/watcher/test/directory_watcher/linux_test.dart
+++ b/pkgs/watcher/test/directory_watcher/linux_test.dart
@@ -23,16 +23,6 @@
         new isInstanceOf<LinuxDirectoryWatcher>());
   });
 
-  test('notifies even if the file contents are unchanged', () {
-    writeFile("a.txt", contents: "same");
-    writeFile("b.txt", contents: "before");
-    startWatcher();
-    writeFile("a.txt", contents: "same");
-    writeFile("b.txt", contents: "after");
-    expectModifyEvent("a.txt");
-    expectModifyEvent("b.txt");
-  });
-
   test('emits events for many nested files moved out then immediately back in',
       () {
     withPermutations((i, j, k) =>
diff --git a/pkgs/watcher/test/directory_watcher/mac_os_test.dart b/pkgs/watcher/test/directory_watcher/mac_os_test.dart
index 8fc2d3e..077787a 100644
--- a/pkgs/watcher/test/directory_watcher/mac_os_test.dart
+++ b/pkgs/watcher/test/directory_watcher/mac_os_test.dart
@@ -36,16 +36,6 @@
     expectAddEvent("dir/newer.txt");
   });
 
-  test('notifies even if the file contents are unchanged', () {
-    writeFile("a.txt", contents: "same");
-    writeFile("b.txt", contents: "before");
-    startWatcher();
-    writeFile("a.txt", contents: "same");
-    writeFile("b.txt", contents: "after");
-    expectModifyEvent("a.txt");
-    expectModifyEvent("b.txt");
-  });
-
   test('emits events for many nested files moved out then immediately back in',
       () {
     withPermutations((i, j, k) =>
diff --git a/pkgs/watcher/test/directory_watcher/polling_test.dart b/pkgs/watcher/test/directory_watcher/polling_test.dart
index 02ed5d2..da29207 100644
--- a/pkgs/watcher/test/directory_watcher/polling_test.dart
+++ b/pkgs/watcher/test/directory_watcher/polling_test.dart
@@ -19,15 +19,6 @@
 
   sharedTests();
 
-  test('does not notify if the file contents are unchanged', () {
-    writeFile("a.txt", contents: "same");
-    writeFile("b.txt", contents: "before");
-    startWatcher();
-    writeFile("a.txt", contents: "same");
-    writeFile("b.txt", contents: "after");
-    expectModifyEvent("b.txt");
-  });
-
   test('does not notify if the modification time did not change', () {
     writeFile("a.txt", contents: "before");
     writeFile("b.txt", contents: "before");
diff --git a/pkgs/watcher/test/directory_watcher/shared.dart b/pkgs/watcher/test/directory_watcher/shared.dart
index fe76a03..f831196 100644
--- a/pkgs/watcher/test/directory_watcher/shared.dart
+++ b/pkgs/watcher/test/directory_watcher/shared.dart
@@ -51,6 +51,16 @@
     expectModifyEvent("file.txt");
   });
 
+  test('notifies even if the file contents are unchanged', () {
+    writeFile("a.txt", contents: "same");
+    writeFile("b.txt", contents: "before");
+    startWatcher();
+    writeFile("a.txt", contents: "same");
+    writeFile("b.txt", contents: "after");
+    expectModifyEvent("a.txt");
+    expectModifyEvent("b.txt");
+  });
+
   test('when the watched directory is deleted, removes all files', () {
     writeFile("dir/a.txt");
     writeFile("dir/b.txt");