diff --git a/wp-admin/includes/file.php b/wp-admin/includes/file.php
index b948d9fad6..ced798288e 100644
--- a/wp-admin/includes/file.php
+++ b/wp-admin/includes/file.php
@@ -445,7 +445,8 @@ function wp_edit_theme_plugin_file( $args ) {
 			}
 		}
 
-		if ( 0 !== validate_file( $real_file, $allowed_files ) ) {
+		// Compare based on relative paths
+		if ( 0 !== validate_file( $file, array_keys( $allowed_files ) ) ) {
 			return new WP_Error( 'disallowed_theme_file', __( 'Sorry, that file cannot be edited.' ) );
 		}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index c919b9e5c6..b1a5c06c7a 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.1-alpha-42243';
+$wp_version = '4.9.1-alpha-42245';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.