diff --git a/lib/dart/pubspec.yaml b/lib/dart/pubspec.yaml
index 7012f5d..53f5450 100644
--- a/lib/dart/pubspec.yaml
+++ b/lib/dart/pubspec.yaml
@@ -23,9 +23,8 @@
 homepage: http://thrift.apache.org
 documentation: http://thrift.apache.org
 environment:
-  sdk: ">=1.12.0 <2.0.0"
+  sdk: ">=1.13.0 <2.0.0"
 dependencies:
-  crypto: "^0.9.0"
   fixnum: "^0.10.2"
   http: "^0.11.3"
   logging: "^0.11.0"