diff --git a/tests/TreeGatewayTest.py b/tests/TreeGatewayTest.py
index 3a29b11c..ef97846b 100644
--- a/tests/TreeGatewayTest.py
+++ b/tests/TreeGatewayTest.py
@@ -131,9 +131,12 @@ def _recvxml(self):
         while not self.xml_reader.msg_available():
             xml_msg = self.gateway.recv()
             if len(xml_msg) == 0:
-                return None
+                self.parser.close()
+                break
             self.assertTrue(type(xml_msg) is bytes)
             self.parser.feed(xml_msg)
+            if hasattr(self.parser, 'flush'):  # >=3.13 and backports
+                self.parser.flush()
 
         return self.xml_reader.pop_msg()