diff --git a/src/poetry/core/json/schemas/poetry-schema.json b/src/poetry/core/json/schemas/poetry-schema.json
index 1a9484431..c499353cc 100644
--- a/src/poetry/core/json/schemas/poetry-schema.json
+++ b/src/poetry/core/json/schemas/poetry-schema.json
@@ -666,7 +666,7 @@
         "generate-setup-file": {
           "type": "boolean",
           "description": "Generate and include a setup.py file in sdist.",
-          "default": true
+          "default": false
         },
         "script": {
           "$ref": "#/definitions/build-script"
diff --git a/src/poetry/core/packages/project_package.py b/src/poetry/core/packages/project_package.py
index b36985e16..5322c0613 100644
--- a/src/poetry/core/packages/project_package.py
+++ b/src/poetry/core/packages/project_package.py
@@ -72,4 +72,4 @@ def urls(self) -> dict[str, Any]:
         return urls
 
     def build_should_generate_setup(self) -> bool:
-        return self.build_config.get("generate-setup-file", True)
+        return self.build_config.get("generate-setup-file", False)