diff --git a/lib/span.dart b/lib/span.dart
index 600506e..771e9e0 100644
--- a/lib/span.dart
+++ b/lib/span.dart
@@ -387,4 +387,7 @@
 class SpanFormatException extends SpanException implements FormatException {
   SpanFormatException(String message, Span span)
       : super(message, span);
+
+  get source => null;
+  int get position => null;
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 9dee45f..e6e749c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,7 +7,7 @@
 #
 # When the minor version is upgraded, you *must* update that version constraint
 # in pub to stay in sync with this.
-version: 0.9.2+3
+version: 0.9.2+4-dev
 author: Dart Team <misc@dartlang.org>
 description: Library to programmatically manipulate source map files.
 homepage: http://www.dartlang.org