diff --git a/pg4wp/core.php b/pg4wp/core.php
index 990c13f..8422ad7 100644
--- a/pg4wp/core.php
+++ b/pg4wp/core.php
@@ -29,6 +29,8 @@ $replaces = array(
 	'<?php'		=> '',
 	'?>'		=> '',
 );
+// Ensure class uses the replaced mysql_ functions rather than mysqli_
+define( 'WP_USE_EXT_MYSQL', true);
 eval( str_replace( array_keys($replaces), array_values($replaces), file_get_contents(ABSPATH.'/wp-includes/wp-db.php')));
 
 // Create wpdb object if not already done