diff --git a/pyes/es.py b/pyes/es.py
index 72d33f13..75ac182a 100644
--- a/pyes/es.py
+++ b/pyes/es.py
@@ -890,7 +890,7 @@ def partial_update(self, index, doc_type, id, doc=None, script=None, params=None
             if params:
                 cmd["params"] = params
             if upsert:
-                cmd["upsert"] = params
+                cmd["upsert"] = upsert
         else:
             cmd = {"doc": doc }
         path = make_path(index, doc_type, id, "_update")