diff --git a/pubspec.yaml b/pubspec.yaml
index 4ae1802..83c59a3 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,9 @@
 name: source_maps
+version: 0.9.0
 author: "Dart Team <misc@dartlang.org>"
 homepage: http://www.dartlang.org
 description: Library to programmatically manipulate source map files.
 dev_dependencies:
-  unittest: any
+  unittest: ">=0.9.0 <0.10.0"
+environment:
+  sdk: ">=0.8.10+6 <2.0.0"