diff --git a/test/test_before_build.py b/test/test_before_build.py
index 3aea640cb..bd6429b82 100644
--- a/test/test_before_build.py
+++ b/test/test_before_build.py
@@ -43,8 +43,8 @@ def test(tmp_path):
     project_with_before_build_asserts.generate(project_dir)
 
     before_build = (
-        """python -c "import sys; open('{project}/pythonversion_bb.txt', 'w').write(sys.version)" && """
-        f'''python -c "import sys; open('{{project}}/pythonprefix_bb.txt', 'w').write({SYS_PREFIX})"'''
+        """python -c "import sys; f = open('{project}/pythonversion_bb.txt', 'w'); f.write(sys.version); f.close()" && """
+        f'''python -c "import sys; f = open('{{project}}/pythonprefix_bb.txt', 'w'); f.write({SYS_PREFIX}); f.close()"'''
     )
 
     # build the wheels
diff --git a/test/test_before_test.py b/test/test_before_test.py
index 59da3135f..755a5afa3 100644
--- a/test/test_before_test.py
+++ b/test/test_before_test.py
@@ -41,8 +41,8 @@ def test(tmp_path, build_frontend_env):
     test_projects.new_c_project().generate(test_project_dir)
 
     before_test_steps = [
-        '''python -c "import os, sys; open('{project}/pythonversion_bt.txt', 'w').write(sys.version)"''',
-        '''python -c "import os, sys; open('{project}/pythonprefix_bt.txt', 'w').write(sys.prefix)"''',
+        '''python -c "import os, sys; f = open('{project}/pythonversion_bt.txt', 'w'); f.write(sys.version); f.close()"''',
+        '''python -c "import os, sys; f = open('{project}/pythonprefix_bt.txt', 'w'); f.write(sys.prefix); f.close()"''',
     ]
 
     if utils.platform == "pyodide":