diff --git a/wp-admin/includes/file.php b/wp-admin/includes/file.php
index ca1dbb5938..ca75342488 100644
--- a/wp-admin/includes/file.php
+++ b/wp-admin/includes/file.php
@@ -890,7 +890,7 @@ function _wp_handle_upload( &$file, $overrides, $time, $action ) {
 
 	// If you override this, you must provide $ext and $type!!
 	$test_type = isset( $overrides['test_type'] ) ? $overrides['test_type'] : true;
-	$mimes     = isset( $overrides['mimes'] ) ? $overrides['mimes'] : false;
+	$mimes     = isset( $overrides['mimes'] ) ? $overrides['mimes'] : null;
 
 	// A correct form post will pass this test.
 	if ( $test_form && ( ! isset( $_POST['action'] ) || $_POST['action'] !== $action ) ) {
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index d146c9195a..10ad8e8b5e 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -3012,9 +3012,9 @@ function wp_get_default_extension_for_mime_type( $mime_type ) {
  *
  * @since 2.0.4
  *
- * @param string   $filename File name or path.
- * @param string[] $mimes    Optional. Array of allowed mime types keyed by their file extension regex.
- *                           Defaults to the result of get_allowed_mime_types().
+ * @param string        $filename File name or path.
+ * @param string[]|null $mimes    Optional. Array of allowed mime types keyed by their file extension regex.
+ *                                Defaults to the result of get_allowed_mime_types().
  * @return array {
  *     Values for the extension and mime type.
  *
@@ -3053,11 +3053,11 @@ function wp_check_filetype( $filename, $mimes = null ) {
  *
  * @since 3.0.0
  *
- * @param string   $file     Full path to the file.
- * @param string   $filename The name of the file (may differ from $file due to $file being
- *                           in a tmp directory).
- * @param string[] $mimes    Optional. Array of allowed mime types keyed by their file extension regex.
- *                           Defaults to the result of get_allowed_mime_types().
+ * @param string        $file     Full path to the file.
+ * @param string        $filename The name of the file (may differ from $file due to $file being
+ *                                in a tmp directory).
+ * @param string[]|null $mimes    Optional. Array of allowed mime types keyed by their file extension regex.
+ *                                Defaults to the result of get_allowed_mime_types().
  * @return array {
  *     Values for the extension, mime type, and corrected filename.
  *
@@ -3239,18 +3239,19 @@ function wp_check_filetype_and_ext( $file, $filename, $mimes = null ) {
 	 * @since 3.0.0
 	 * @since 5.1.0 The $real_mime parameter was added.
 	 *
-	 * @param array        $wp_check_filetype_and_ext {
+	 * @param array         $wp_check_filetype_and_ext {
 	 *     Values for the extension, mime type, and corrected filename.
 	 *
 	 *     @type string|false $ext             File extension, or false if the file doesn't match a mime type.
 	 *     @type string|false $type            File mime type, or false if the file doesn't match a mime type.
 	 *     @type string|false $proper_filename File name with its correct extension, or false if it cannot be determined.
 	 * }
-	 * @param string       $file                      Full path to the file.
-	 * @param string       $filename                  The name of the file (may differ from $file due to
-	 *                                                $file being in a tmp directory).
-	 * @param string[]     $mimes                     Array of mime types keyed by their file extension regex.
-	 * @param string|false $real_mime                 The actual mime type or false if the type cannot be determined.
+	 * @param string        $file                      Full path to the file.
+	 * @param string        $filename                  The name of the file (may differ from $file due to
+	 *                                                 $file being in a tmp directory).
+	 * @param string[]|null $mimes                     Array of mime types keyed by their file extension regex, or null if
+	 *                                                 none were provided.
+	 * @param string|false  $real_mime                 The actual mime type or false if the type cannot be determined.
 	 */
 	return apply_filters( 'wp_check_filetype_and_ext', compact( 'ext', 'type', 'proper_filename' ), $file, $filename, $mimes, $real_mime );
 }
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 7a2c14f4d4..0812eb8cfa 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55871';
+$wp_version = '6.3-alpha-55872';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.