diff --git a/classes/GS_DataObject.php b/classes/GS_DataObject.php
index 6d4873639e..47125f2438 100644
--- a/classes/GS_DataObject.php
+++ b/classes/GS_DataObject.php
@@ -137,6 +137,20 @@ class GS_DataObject extends DB_DataObject
         return $res;
     }
 
+    // DB_DataObject's joinAdd calls DB_DataObject::factory explicitly, so our factory-override doesn't work
+    public function joinAdd($obj = false, $joinType='INNER', $joinAs=false, $joinCol=false)
+    {
+        // avoid those annoying PEAR::DB strict standards warnings it causes
+        $old = error_reporting();
+        error_reporting(error_reporting() & ~E_STRICT);
+
+        $res = parent::joinAdd($obj, $joinType, $joinAs, $joinCol);
+
+        // reset
+        error_reporting($old);
+        return $res;
+    }
+
     public function links()
     {
         // avoid those annoying PEAR::DB strict standards warnings it causes