diff --git a/wp-admin/includes/update-core.php b/wp-admin/includes/update-core.php
index 41aeb71485..50f50ddc53 100644
--- a/wp-admin/includes/update-core.php
+++ b/wp-admin/includes/update-core.php
@@ -337,7 +337,7 @@ function update_core($from, $to) {
 	$required_mysql_version = '5.0';
 	$wp_version = '3.3';
 	$php_compat     = version_compare( $php_version, $required_php_version, '>=' );
-	if ( file_exists( WP_CONTENT_DIR . '/db.php' ) && empty( $this->is_mysql ) )
+	if ( file_exists( WP_CONTENT_DIR . '/db.php' ) && empty( $wpdb->is_mysql ) )
 		$mysql_compat = true;
 	else
 		$mysql_compat = version_compare( $mysql_version, $required_mysql_version, '>=' );