diff --git a/pypureomapi.py b/pypureomapi.py
index 825ebc5..3c906a3 100644
--- a/pypureomapi.py
+++ b/pypureomapi.py
@@ -1214,7 +1214,7 @@ def __lookup(self, ltype, **kwargs):
 			elif _k == "name":
 				msg.obj.append((b"name", kwargs[k].encode('utf-8')))
 			else:
-				msg.obj.append((str(k).encode(), kwargs[k].encode('utf-8')))
+				msg.obj.append((str(_k).encode(), kwargs[k].encode('utf-8')))
 		response = self.query_server(msg)
 		if response.opcode != OMAPI_OP_UPDATE:
 			raise OmapiErrorNotFound()