diff --git a/pubspec.yaml b/pubspec.yaml
index cf8226b..8d9c88d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -16,7 +16,7 @@
     path: test_package
   unittest: '>=0.10.0 <0.12.0'
 environment:
-  sdk: '>=1.4.0 <2.0.0'
+  sdk: ">=1.9.0-dev.7.1 <2.0.0"
 transformers:
 - initialize/build/loader_replacer:
     $include: lib/initialize.dart