diff --git a/src/wp-includes/wp-db.php b/src/wp-includes/wp-db.php
index ac2d645e03..91803e7d62 100644
--- a/src/wp-includes/wp-db.php
+++ b/src/wp-includes/wp-db.php
@@ -8,7 +8,10 @@
  * @package WordPress
  */
 
-_deprecated_file( basename( __FILE__ ), '6.1.0', WPINC . '/class-wpdb.php' );
+if ( function_exists( '_deprecated_file' ) ) {
+	// Note: WPINC may not be defined yet, so 'wp-includes' is used here.
+	_deprecated_file( basename( __FILE__ ), '6.1.0', 'wp-includes/class-wpdb.php' );
+}
 
 /** wpdb class */
-require_once ABSPATH . WPINC . '/class-wpdb.php';
+require_once ABSPATH . 'wp-includes/class-wpdb.php';