diff --git a/frankenphp.c b/frankenphp.c
index a9cd534dc5..6592852dda 100644
--- a/frankenphp.c
+++ b/frankenphp.c
@@ -63,7 +63,6 @@ frankenphp_config frankenphp_get_config() {
   };
 }
 
-bool should_filter_var = 0;
 __thread uintptr_t thread_index;
 __thread bool is_worker_thread = false;
 __thread zval *os_environment = NULL;
@@ -613,8 +612,7 @@ void frankenphp_register_trusted_var(zend_string *z_key, char *value,
   }
   size_t new_val_len = val_len;
 
-  if (!should_filter_var ||
-      sapi_module.input_filter(PARSE_SERVER, ZSTR_VAL(z_key), &value,
+  if (sapi_module.input_filter(PARSE_SERVER, ZSTR_VAL(z_key), &value,
                                new_val_len, &new_val_len)) {
     zval z_value;
     ZVAL_STRINGL_FAST(&z_value, value, new_val_len);
@@ -743,8 +741,7 @@ void frankenphp_register_variable_safe(char *key, char *val, size_t val_len,
     val = "";
   }
   size_t new_val_len = val_len;
-  if (!should_filter_var ||
-      sapi_module.input_filter(PARSE_SERVER, key, &val, new_val_len,
+  if (sapi_module.input_filter(PARSE_SERVER, key, &val, new_val_len,
                                &new_val_len)) {
     php_register_variable_safe(key, val, new_val_len, track_vars_array);
   }
@@ -916,12 +913,6 @@ static void *php_main(void *arg) {
 
   frankenphp_sapi_module.startup(&frankenphp_sapi_module);
 
-  /* check if a default filter is set in php.ini and only filter if
-   * it is, this is deprecated and will be removed in PHP 9 */
-  char *default_filter;
-  cfg_get_string("filter.default", &default_filter);
-  should_filter_var = default_filter != NULL;
-
   go_frankenphp_main_thread_is_ready();
 
   /* channel closed, shutdown gracefully */
diff --git a/frankenphp_test.go b/frankenphp_test.go
index 2df44ebfc5..54c7043305 100644
--- a/frankenphp_test.go
+++ b/frankenphp_test.go
@@ -286,6 +286,46 @@ func testInput(t *testing.T, opts *testOptions) {
 	}, opts)
 }
 
+func TestFilterInputDefault_module(t *testing.T) { testFilterInputDefault(t, nil) }
+func TestFilterInputDefault_worker(t *testing.T) {
+	testFilterInputDefault(t, &testOptions{workerScript: "filter.php"})
+}
+func testFilterInputDefault(t *testing.T, opts *testOptions) {
+	if opts == nil {
+		opts = &testOptions{}
+	}
+	opts.initOpts = append(opts.initOpts, frankenphp.WithPhpIni(map[string]string{
+		"filter.default": "string.tolower",
+	}))
+	runTest(t, func(handler func(http.ResponseWriter, *http.Request), _ *httptest.Server, i int) {
+		req := httptest.NewRequest("GET", "http://example.com/filter.php", nil)
+		w := httptest.NewRecorder()
+		handler(w, req)
+
+		resp := w.Result()
+		body, _ := io.ReadAll(resp.Body)
+
+		assert.Equal(t, "GET", string(body))
+	}, opts)
+}
+
+func TestFilterInput_module(t *testing.T) { testFilterInput(t, nil) }
+func TestFilterInput_worker(t *testing.T) {
+	testFilterInput(t, &testOptions{workerScript: "filter.php"})
+}
+func testFilterInput(t *testing.T, opts *testOptions) {
+	runTest(t, func(handler func(http.ResponseWriter, *http.Request), _ *httptest.Server, i int) {
+		req := httptest.NewRequest("GET", "http://example.com/filter.php", nil)
+		w := httptest.NewRecorder()
+		handler(w, req)
+
+		resp := w.Result()
+		body, _ := io.ReadAll(resp.Body)
+
+		assert.Equal(t, "GET", string(body))
+	}, opts)
+}
+
 func TestPostSuperGlobals_module(t *testing.T) { testPostSuperGlobals(t, nil) }
 func TestPostSuperGlobals_worker(t *testing.T) {
 	testPostSuperGlobals(t, &testOptions{workerScript: "super-globals.php"})
diff --git a/testdata/filter.php b/testdata/filter.php
new file mode 100644
index 0000000000..b8e1d41701
--- /dev/null
+++ b/testdata/filter.php
@@ -0,0 +1,6 @@
+<?php
+require_once __DIR__.'/_executor.php';
+
+return function () {
+    echo strtoupper(filter_input(INPUT_SERVER, "REQUEST_METHOD", FILTER_UNSAFE_RAW, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH) ?? "");
+};