diff --git a/.travis.yml b/.travis.yml
index 4fb40c9..d3bd604 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,7 @@
 language: dart
-
+sudo: false
 dart:
+  - stable
   - dev
-  # Currently requires a dev-branch in order to use properly.
-  # - stable
-
+  - 1.21.0
 script: ./tool/presubmit.sh
diff --git a/pubspec.yaml b/pubspec.yaml
index a0b4925..93afdf4 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,7 +4,7 @@
 description: Support for marking objects as observable
 homepage: https://github.com/dart-lang/observable
 environment:
-  sdk: '>=1.19.0 <2.0.0'
+  sdk: '>=1.21.0 <2.0.0'
 dependencies:
   collection: '^1.11.0'
   meta: '^1.0.4'