diff --git a/frankenphp.c b/frankenphp.c
index 07f9fdf67..c25a3505f 100644
--- a/frankenphp.c
+++ b/frankenphp.c
@@ -1227,7 +1227,7 @@ int frankenphp_execute_script(char *file_name) {
 
   zend_destroy_file_handle(&file_handle);
 
-  /* Reset the sandboxed environment */
+  /* Reset the sandboxed environment if it is in use */
   if (sandboxed_env != NULL) {
     zend_hash_release(sandboxed_env);
     sandboxed_env = NULL;
diff --git a/frankenphp_test.go b/frankenphp_test.go
index f8279d80a..df17219f3 100644
--- a/frankenphp_test.go
+++ b/frankenphp_test.go
@@ -141,8 +141,8 @@ func TestMain(m *testing.M) {
 		slog.SetDefault(slog.New(slog.DiscardHandler))
 	}
 
-	// setup custom environment var for TestWorkerHasOSEnvironmentVariableInSERVER
-	if os.Setenv("CUSTOM_OS_ENV_VARIABLE", "custom_env_variable_value") != nil {
+	// setup custom environment var for TestWorkerHasOSEnvironmentVariableInSERVER and TestPhpIni
+	if os.Setenv("CUSTOM_OS_ENV_VARIABLE", "custom_env_variable_value") != nil || os.Setenv("LITERAL_ZERO", "0") != nil {
 		fmt.Println("Failed to set environment variable for tests")
 		os.Exit(1)
 	}
@@ -162,14 +162,12 @@ func testHelloWorld(t *testing.T, opts *testOptions) {
 }
 
 func TestEnvVarsInPhpIni(t *testing.T) {
-	t.Setenv("OPCACHE_ENABLE", "0")
-
 	runTest(t, func(handler func(http.ResponseWriter, *http.Request), _ *httptest.Server, _ int) {
 		body, _ := testGet("http://example.com/ini.php?key=opcache.enable", handler, t)
 		assert.Equal(t, "opcache.enable:0", body)
 	}, &testOptions{
 		phpIni: map[string]string{
-			"opcache.enable": "${OPCACHE_ENABLE}",
+			"opcache.enable": "${LITERAL_ZERO}",
 		},
 	})
 }
@@ -1305,20 +1303,26 @@ func TestSessionNoLeakAfterExit_worker(t *testing.T) {
 }
 
 func TestOpcachePreload_module(t *testing.T) {
-	testOpcachePreload(t, &testOptions{env: map[string]string{"TEST": "123"}})
+	testOpcachePreload(t, &testOptions{env: map[string]string{"TEST": "123"}, realServer: true})
 }
 
 func TestOpcachePreload_worker(t *testing.T) {
-	testOpcachePreload(t, &testOptions{workerScript: "preload-check.php", nbWorkers: 1, nbParallelRequests: 1, env: map[string]string{"TEST": "123"}})
+	testOpcachePreload(t, &testOptions{workerScript: "preload-check.php", env: map[string]string{"TEST": "123"}, realServer: true})
 }
 
 func testOpcachePreload(t *testing.T, opts *testOptions) {
+	if frankenphp.Version().VersionID <= 80300 {
+		t.Skip("This test is only supported in PHP 8.3 and above")
+		return
+	}
+
 	cwd, _ := os.Getwd()
 	preloadScript := cwd + "/testdata/preload.php"
 
 	u, err := user.Current()
 	require.NoError(t, err)
 
+	// use opcache.log_verbosity_level:4 for debugging
 	opts.phpIni = map[string]string{
 		"opcache.enable":       "1",
 		"opcache.preload":      preloadScript,