diff --git a/third_party/search_fields/pi.search_fields.php b/third_party/search_fields/pi.search_fields.php
index 6d2aacf..2286e4a 100644
--- a/third_party/search_fields/pi.search_fields.php
+++ b/third_party/search_fields/pi.search_fields.php
@@ -130,6 +130,13 @@ function Search_fields()
 					$search_cat = true;
 				}
 				
+				// search category ID 
+				else if ($field_name =="cat_id") 
+				{
+					$field_sql = 'ct.cat_id';
+					$search_cat = true;
+				}
+				
 				// search category description 
 				else if ($field_name =="cat_description") 
 				{