diff --git a/pubspec.yaml b/pubspec.yaml
index c733fdb..271ddb2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,7 +3,7 @@ description: Random select a nice skill for Ring Fit Adventure(RFA).
 publish_to: "none"
 version: 1.0.0+1
 environment:
-  sdk: ">=2.18.4 <3.0.0"
+  sdk: "<4.0.0"
 dependencies:
   flutter:
     sdk: flutter