diff --git a/src/wp-includes/option.php b/src/wp-includes/option.php
index 9f7cc8698e..7715426608 100644
--- a/src/wp-includes/option.php
+++ b/src/wp-includes/option.php
@@ -44,12 +44,19 @@ function get_option( $option, $default = false ) {
 	 *
 	 * @since 1.5.0
 	 * @since 4.4.0 The `$option` parameter was added.
+	 * @since 4.9.0 The `$default` parameter was added.
 	 *
-	 * @param bool|mixed $pre_option Value to return instead of the option value.
-	 *                               Default false to skip it.
+	 *
+	 * @param bool|mixed $pre_option The value to return instead of the option value. This differs from
+	 *                               `$default`, which is used as the fallback value in the event the option
+	 *                               doesn't exist elsewhere in get_option(). Default false (to skip past the
+	 *                               short-circuit).
 	 * @param string     $option     Option name.
+	 * @param mixed      $default    The fallback value to return if the option does not exist.
+	 *                               Default is false.
 	 */
-	$pre = apply_filters( "pre_option_{$option}", false, $option );
+	$pre = apply_filters( "pre_option_{$option}", false, $option, $default );
+
 	if ( false !== $pre )
 		return $pre;
 
@@ -1116,12 +1123,18 @@ function get_network_option( $network_id, $option, $default = false ) {
 	 * @since 3.0.0
 	 * @since 4.4.0 The `$option` parameter was added.
 	 * @since 4.7.0 The `$network_id` parameter was added.
+	 * @since 4.9.0 The `$default` parameter was added.
 	 *
-	 * @param mixed  $pre_option The default value to return if the option does not exist.
+	 * @param mixed  $pre_option The value to return instead of the option value. This differs from
+	 *                           `$default`, which is used as the fallback value in the event the
+	 *                           option doesn't exist elsewhere in get_network_option(). Default
+	 *                           is false (to skip past the short-circuit).
 	 * @param string $option     Option name.
 	 * @param int    $network_id ID of the network.
+	 * @param mixed  $default    The fallback value to return if the option does not exist.
+	 *                           Default is false.
 	 */
-	$pre = apply_filters( "pre_site_option_{$option}", false, $option, $network_id );
+	$pre = apply_filters( "pre_site_option_{$option}", false, $option, $network_id, $default );
 
 	if ( false !== $pre ) {
 		return $pre;