diff --git src/wp-includes/class.wp-scripts.php src/wp-includes/class.wp-scripts.php
index 0f38a48618..4979779350 100644
--- src/wp-includes/class.wp-scripts.php
+++ src/wp-includes/class.wp-scripts.php
@@ -562,7 +562,7 @@ class WP_Scripts extends WP_Dependencies {
 	 * @param string $path   Optional. The full file path to the directory containing translation files.
 	 * @return bool True if the text domain was registered, false if not.
 	 */
-	public function set_translations( $handle, $domain = 'default', $path = null ) {
+	public function set_translations( $handle, $domain = 'default', $path = '' ) {
 		if ( ! isset( $this->registered[ $handle ] ) ) {
 			return false;
 		}
diff --git src/wp-includes/functions.wp-scripts.php src/wp-includes/functions.wp-scripts.php
index 82d3685672..e45e9a0fb1 100644
--- src/wp-includes/functions.wp-scripts.php
+++ src/wp-includes/functions.wp-scripts.php
@@ -237,7 +237,7 @@ function wp_localize_script( $handle, $object_name, $l10n ) {
  * @param string $path   Optional. The full file path to the directory containing translation files.
  * @return bool True if the text domain was successfully localized, false otherwise.
  */
-function wp_set_script_translations( $handle, $domain = 'default', $path = null ) {
+function wp_set_script_translations( $handle, $domain = 'default', $path = '' ) {
 	global $wp_scripts;
 
 	if ( ! ( $wp_scripts instanceof WP_Scripts ) ) {
diff --git src/wp-includes/l10n.php src/wp-includes/l10n.php
index 3922805a87..db1cae60fd 100644
--- src/wp-includes/l10n.php
+++ src/wp-includes/l10n.php
@@ -1008,7 +1008,7 @@ function load_child_theme_textdomain( $domain, $path = false ) {
  * @return string|false The translated strings in JSON encoding on success,
  *                      false if the script textdomain could not be loaded.
  */
-function load_script_textdomain( $handle, $domain = 'default', $path = null ) {
+function load_script_textdomain( $handle, $domain = 'default', $path = '' ) {
 	$wp_scripts = wp_scripts();
 
 	if ( ! isset( $wp_scripts->registered[ $handle ] ) ) {