diff --git a/pubspec.yaml b/pubspec.yaml
index ba49c76..8b74954 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,7 +7,7 @@ executables:
   btool: btool
 
 environment:
-  sdk: '>=2.18.0 <3.0.0'
+  sdk: '>=2.18.0 <4.0.0'
 
 dependencies:
   args: ^2.3.1