diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 07459c04..4f693977 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -38,7 +38,7 @@ jobs:
           CARGO_TARGET_DIR: "/host${{ runner.temp }}/cargo_build"
           CARGO_HOME: "/host${{ runner.temp }}/cargo_home"
           CIBW_PLATFORM: "linux"
-          CIBW_ENVIRONMENT_LINUX: "SCALIB_NTL=1"
+          CIBW_ENVIRONMENT_LINUX: "SCALIB_NTL=1 RUST_BACKTRACE=1 SCALIB_X86_64_V3=1"
       - uses: actions/upload-artifact@v4
         with:
           name: dist-wheel_linux-${{ matrix.arch }}
@@ -157,7 +157,7 @@ jobs:
 
   build_wheel_windows:
     name: Build wheel on Windows
-    runs-on: windows-2019
+    runs-on: windows-2025
     strategy:
       fail-fast: false
       matrix:
@@ -182,6 +182,7 @@ jobs:
           CIBW_PLATFORM: "windows"
           CIBW_TEST_COMMAND: pytest {project}/tests
           CIBW_TEST_REQUIRES: "-r tests/requirements.txt"
+          CIBW_ENVIRONMENT: "RUST_BACKTRACE=1 SCALIB_X86_64_V3=1"
       - uses: actions/upload-artifact@v4
         with:
           name: dist-wheel_windows-${{ matrix.arch }}
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 8a7495b3..7896ac7d 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -5,6 +5,11 @@ Changelog
 Not released
 ------------
 
+v0.6.4 (2025/06/24)
+-------------------
+
+* Fix build system (no more unwanted packages) and fix CI configuration (#203).
+
 v0.6.3 (2025/05/06)
 -------------------
 
diff --git a/pyproject.toml b/pyproject.toml
index 1a580e81..f3028f4c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,6 +31,11 @@ Repository = "https://github.com/simple-crypto/SCALib.git"
 Issues = "https://github.com/simple-crypto/SCALib/issues"
 Changelog = "https://github.com/simple-crypto/SCALib/blob/main/CHANGELOG.rst"
 
+[tool.setuptools.packages.find]
+exclude = ["scalib_ext*"]
+where = ["src"]
+namespaces = false
+
 
 [tool.setuptools_scm]
 version_file = "src/scalib/version.py"
@@ -46,6 +51,3 @@ build = ["cp310-*"]
 skip = ["*musllinux*"]
 archs = "auto64"
 environment-pass = ["CARGO_TARGET_DIR", "CARGO_HOME"]
-[tool.cibuildwheel.environment]
-RUST_BACKTRACE = "full"
-SCALIB_X86_64_V3 = "1"