diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3c5c9e60..9858e272 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,9 +10,12 @@ jobs:
       - uses: DeterminateSystems/nix-installer-action@main
       - uses: DeterminateSystems/magic-nix-cache-action@main
       - run: echo "${GITHUB_WORKSPACE}" >> $GITHUB_PATH
-      - run: nix flake check --print-build-logs
+      - run: nix build .#simple-tests --print-build-logs
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+        uses: codecov/codecov-action@v4
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          files: ./result/coverage.xml
   lint:
     runs-on: ubuntu-latest
     steps:
diff --git a/.gitignore b/.gitignore
index ad8e8b92..fca52d7c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -81,3 +81,4 @@ venv/
 venv-*/
 .venv/
 node_modules/
+result/
diff --git a/flake.nix b/flake.nix
index 0ec8d8f8..d5299d8c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -102,8 +102,18 @@
           doCheck = false;
         };
       in {
-        checks = rec {
-          default = simple-tests;
+        packages = rec {
+          default = tested;
+          tested = poetry.mkPoetryApplication {
+            inherit (tested-env)
+              projectDir python overrides propagatedBuildInputs;
+            doCheck = false;
+            postInstall = ''
+              wrapProgram "$out/bin/tested" \
+                --prefix NODE_PATH : ${ast}/lib/node_modules
+            '';
+          };
+          devShell = self.outputs.devShells.${system}.default;
           simple-tests = pkgs.stdenvNoCC.mkDerivation {
             name = "simple-tests";
             src = self;
@@ -117,23 +127,10 @@
               poetry run pytest -n auto --cov=tested --cov-report=xml tests/test_functionality.py
             '';
             installPhase = ''
-              touch $out # it worked!
-            '';
-          };
-        };
-
-        packages = rec {
-          default = tested;
-          tested = poetry.mkPoetryApplication {
-            inherit (tested-env)
-              projectDir python overrides propagatedBuildInputs;
-            doCheck = false;
-            postInstall = ''
-              wrapProgram "$out/bin/tested" \
-                --prefix NODE_PATH : ${ast}/lib/node_modules
+              mkdir -p $out
+              cp coverage.xml $out/coverage.xml
             '';
           };
-          devShell = self.outputs.devShells.${system}.default;
         };
 
         devShells = rec {