diff --git a/tag-dropdown-widget.php b/tag-dropdown-widget.php
index 7d39d82c65f86bc8ed00611323dadabeb3fb9a2f..e5259d1be39d9496d426c0929722a38f44e39580 100644
--- a/tag-dropdown-widget.php
+++ b/tag-dropdown-widget.php
@@ -361,6 +361,8 @@ class taxonomy_dropdown_widget_plugin {
 		return $options_sanitized;
 	}
 }
+
+// Prior to introduction of singleton, plugin was instantiated in a global. Continuing to do so improves backwards compatibility.
 $GLOBALS['taxonomy_dropdown_widget_plugin'] = taxonomy_dropdown_widget_plugin::get_instance();
 
 /**