diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8f9c01a..15112fd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 0.13.3+3
+
+* Add an explicit default value for the `allowTrailingOptions` parameter to `new
+  ArgParser()`. This doesn't change the behavior at all; the option already
+  defaulted to `false`, and passing in `null` still works.
+
 ## 0.13.3+2
 
 * Documentation fixes.
diff --git a/lib/src/arg_parser.dart b/lib/src/arg_parser.dart
index 0b81fed..f5ce41a 100644
--- a/lib/src/arg_parser.dart
+++ b/lib/src/arg_parser.dart
@@ -35,12 +35,12 @@
   /// after it finds an argument that is neither an option nor a command.
   /// This allows options to be specified after regular arguments. Defaults to
   /// `false`.
-  factory ArgParser({bool allowTrailingOptions}) => new ArgParser._(
+  factory ArgParser({bool allowTrailingOptions: false}) => new ArgParser._(
       <String, Option>{}, <String, ArgParser>{},
       allowTrailingOptions: allowTrailingOptions);
 
   ArgParser._(Map<String, Option> options, Map<String, ArgParser> commands,
-      {bool allowTrailingOptions})
+      {bool allowTrailingOptions: false})
       : this._options = options,
         this.options = new UnmodifiableMapView(options),
         this._commands = commands,
diff --git a/pubspec.yaml b/pubspec.yaml
index c51fad7..326ef0e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: args
-version: 0.13.3+2
+version: 0.13.3+3
 author: "Dart Team <misc@dartlang.org>"
 homepage: https://github.com/dart-lang/args
 description: >