diff --git a/wp-admin/includes/plugin.php b/wp-admin/includes/plugin.php
index f60489064a..c6e7ecfbc0 100644
--- a/wp-admin/includes/plugin.php
+++ b/wp-admin/includes/plugin.php
@@ -940,11 +940,11 @@ function validate_active_plugins() {
 /**
  * Validate the plugin path.
  *
- * Checks that the file exists and is a valid file. See validate_file().
+ * Checks that the main plugin file exists and is a valid plugin. See validate_file().
  *
  * @since 2.5.0
  *
- * @param string $plugin Plugin Path.
+ * @param string $plugin Path to the main plugin file from plugins directory.
  * @return WP_Error|int 0 on success, WP_Error on failure.
  */
 function validate_plugin($plugin) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index f05d4a727e..4edc7edbfb 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-39888';
+$wp_version = '4.8-alpha-39889';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.