diff --git a/core/pubspec.yaml b/core/pubspec.yaml
index ed506da..73f3b0c 100644
--- a/core/pubspec.yaml
+++ b/core/pubspec.yaml
@@ -3,7 +3,7 @@ description: dartstruct is an annotation processor generator using source_gen an
 version: 0.0.0
 
 environment:
-  sdk: '>=2.7.0 <3.0.0'
+  sdk: '<4.0.0'
 
 dependencies:
   path: ^1.6.0
diff --git a/generator/pubspec.yaml b/generator/pubspec.yaml
index 7aabf92..0967d22 100644
--- a/generator/pubspec.yaml
+++ b/generator/pubspec.yaml
@@ -3,7 +3,7 @@ description: dartstruct generator is an annotation processor generator using sou
 version: 0.0.0
 
 environment:
-  sdk: '>=2.7.0 <3.0.0'
+  sdk: '<4.0.0'
 
 dependencies:
   build: ^1.2.2
diff --git a/integration_tests/pubspec.yaml b/integration_tests/pubspec.yaml
index ec9a93d..a241582 100644
--- a/integration_tests/pubspec.yaml
+++ b/integration_tests/pubspec.yaml
@@ -3,7 +3,7 @@ description:
 version: 0.0.0
 
 environment:
-  sdk: '>=2.7.0 <3.0.0'
+  sdk: '<4.0.0'
 
 dependencies:
   dartstruct: