diff --git a/recipes/CMakeProject/recipe.py b/recipes/CMakeProject/recipe.py
index f00e10c..e2e30e4 100644
--- a/recipes/CMakeProject/recipe.py
+++ b/recipes/CMakeProject/recipe.py
@@ -11,7 +11,7 @@ def cook(env: Environment, project_root: str, generate_args: 'list[str]' = [], b
     config = env['BUILD_TYPE']
     build_dir = os.path.join(project_root, f'build_{config}')
     install_dir = os.path.join(project_root, f'install_{config}')
-    is_built = os.path.exists(os.path.join(project_root, _BUILT_STAMPFILE))
+    is_built = os.path.exists(os.path.join(install_dir, _BUILT_STAMPFILE))
     if not is_built or env['UPDATE_REPOSITORIES']:
         print(f'Building {project_root}, config {config}')
         os.makedirs(build_dir, exist_ok=True)
@@ -24,7 +24,7 @@ def cook(env: Environment, project_root: str, generate_args: 'list[str]' = [], b
         subprocess.run(('cmake', '-G', 'Ninja', '-B', build_dir, f'-DCMAKE_BUILD_TYPE={build_type}', f'-DCMAKE_INSTALL_PREFIX={install_dir}', *generate_args, project_root), stdout=sys.stdout, stderr=sys.stderr, check=True)
         subprocess.run(('cmake', '--build', *build_args, build_dir), stdout=sys.stdout, stderr=sys.stderr, check=True)
         subprocess.run(('cmake', '--install', *install_args, build_dir), stdout=sys.stdout, stderr=sys.stderr, check=True)
-        pathlib.Path(project_root, _BUILT_STAMPFILE).touch()
+        pathlib.Path(install_dir, _BUILT_STAMPFILE).touch()
 
     return {
         'LIBPATH': [os.path.join(install_dir, 'lib')],