diff --git a/bin/internal/update_dart_sdk.sh b/bin/internal/update_dart_sdk.sh
index 7b28056079..630e3157a3 100755
--- a/bin/internal/update_dart_sdk.sh
+++ b/bin/internal/update_dart_sdk.sh
@@ -27,11 +27,9 @@ if [ ! -f "$ENGINE_STAMP" ] || [ "$ENGINE_VERSION" != `cat "$ENGINE_STAMP"` ]; t
   case "$(uname -s)" in
     Darwin)
       DART_ZIP_NAME="dart-sdk-darwin-x64.zip"
-      IS_USER_EXECUTABLE="-perm +100"
       ;;
     Linux)
       DART_ZIP_NAME="dart-sdk-linux-x64.zip"
-      IS_USER_EXECUTABLE="-perm /u+x"
       ;;
     *)
       echo "Unknown operating system. Cannot install Dart SDK."
@@ -50,7 +48,7 @@ if [ ! -f "$ENGINE_STAMP" ] || [ "$ENGINE_VERSION" != `cat "$ENGINE_STAMP"` ]; t
 
   # install the new sdk
   rm -rf -- "$DART_SDK_PATH"
-  mkdir -m 755 -p -- "$DART_SDK_PATH"
+  mkdir -p -- "$DART_SDK_PATH"
   DART_SDK_ZIP="$FLUTTER_ROOT/bin/cache/$DART_ZIP_NAME"
 
   curl --continue-at - --location --output "$DART_SDK_ZIP" "$DART_SDK_URL" 2>&1 || {
@@ -72,8 +70,6 @@ if [ ! -f "$ENGINE_STAMP" ] || [ "$ENGINE_VERSION" != `cat "$ENGINE_STAMP"` ]; t
     exit 1
   }
   rm -f -- "$DART_SDK_ZIP"
-  find "$DART_SDK_PATH" -type d -exec chmod 755 {} \;
-  find "$DART_SDK_PATH" -type f $IS_USER_EXECUTABLE -exec chmod a+x,a+r {} \;
   echo "$ENGINE_VERSION" > "$ENGINE_STAMP"
 
   # delete any temporary sdk path
diff --git a/packages/flutter_tools/lib/src/base/os.dart b/packages/flutter_tools/lib/src/base/os.dart
index 6736e2defc..54f5964146 100644
--- a/packages/flutter_tools/lib/src/base/os.dart
+++ b/packages/flutter_tools/lib/src/base/os.dart
@@ -25,15 +25,7 @@ abstract class OperatingSystemUtils {
   OperatingSystemUtils._private();
 
   /// Make the given file executable. This may be a no-op on some platforms.
-  void makeExecutable(File file);
-
-  /// Updates the specified file system [entity] to have the file mode
-  /// bits set to the value defined by [mode], which can be specified in octal
-  /// (e.g. `644`) or symbolically (e.g. `u+x`).
-  ///
-  /// On operating systems that do not support file mode bits, this will be a
-  /// no-op.
-  void chmod(FileSystemEntity entity, String mode);
+  ProcessResult makeExecutable(File file);
 
   /// Return the path (with symlinks resolved) to the given executable, or null
   /// if `which` was not able to locate the binary.
@@ -86,13 +78,8 @@ class _PosixUtils extends OperatingSystemUtils {
   _PosixUtils() : super._private();
 
   @override
-  void makeExecutable(File file) {
-    chmod(file, 'a+x');
-  }
-
-  @override
-  void chmod(FileSystemEntity entity, String mode) {
-    processManager.runSync(<String>['chmod', mode, entity.path]);
+  ProcessResult makeExecutable(File file) {
+    return processManager.runSync(<String>['chmod', 'a+x', file.path]);
   }
 
   @override
@@ -165,11 +152,11 @@ class _PosixUtils extends OperatingSystemUtils {
 class _WindowsUtils extends OperatingSystemUtils {
   _WindowsUtils() : super._private();
 
+  // This is a no-op.
   @override
-  void makeExecutable(File file) {}
-
-  @override
-  void chmod(FileSystemEntity entity, String mode) {}
+  ProcessResult makeExecutable(File file) {
+    return ProcessResult(0, 0, null, null);
+  }
 
   @override
   List<File> _which(String execName, {bool all = false}) {
diff --git a/packages/flutter_tools/lib/src/cache.dart b/packages/flutter_tools/lib/src/cache.dart
index 63e3d6586b..dfa3377255 100644
--- a/packages/flutter_tools/lib/src/cache.dart
+++ b/packages/flutter_tools/lib/src/cache.dart
@@ -145,10 +145,8 @@ class Cache {
   /// Return a directory in the cache dir. For `pkg`, this will return `bin/cache/pkg`.
   Directory getCacheDir(String name) {
     final Directory dir = fs.directory(fs.path.join(getRoot().path, name));
-    if (!dir.existsSync()) {
+    if (!dir.existsSync())
       dir.createSync(recursive: true);
-      os.chmod(dir, '755');
-    }
     return dir;
   }
 
@@ -196,10 +194,8 @@ class Cache {
     final Directory thirdPartyDir = getArtifactDirectory('third_party');
 
     final Directory serviceDir = fs.directory(fs.path.join(thirdPartyDir.path, serviceName));
-    if (!serviceDir.existsSync()) {
+    if (!serviceDir.existsSync())
       serviceDir.createSync(recursive: true);
-      os.chmod(serviceDir, '755');
-    }
 
     final File cachedFile = fs.file(fs.path.join(serviceDir.path, url.pathSegments.last));
     if (!cachedFile.existsSync()) {
@@ -556,16 +552,13 @@ class FlutterEngine extends CachedArtifact {
     return result;
   }
 
+
   void _makeFilesExecutable(Directory dir) {
-    os.chmod(dir, 'a+r,a+x');
-    for (FileSystemEntity entity in dir.listSync(recursive: true)) {
+    for (FileSystemEntity entity in dir.listSync()) {
       if (entity is File) {
-        final FileStat stat = entity.statSync();
-        final bool isUserExecutable = ((stat.mode >> 6) & 0x1) == 1;
-        if (entity.basename == 'flutter_tester' || isUserExecutable) {
-          // Make the file readable and executable by all users.
-          os.chmod(entity, 'a+r,a+x');
-        }
+        final String name = fs.path.basename(entity.path);
+        if (name == 'flutter_tester')
+          os.makeExecutable(entity);
       }
     }
   }