diff --git a/petl/test/io/test_xml.py b/petl/test/io/test_xml.py
index 2305f5a2..e1dc9df6 100644
--- a/petl/test/io/test_xml.py
+++ b/petl/test/io/test_xml.py
@@ -308,15 +308,15 @@ def test_fromxml_entity():
 
 
 def _check_toxml(table, expected, check=(), **kwargs):
-    with NamedTemporaryFile(delete=True, mode='wt') as f:
+    with NamedTemporaryFile(delete=True, suffix='.xml') as f:
         filename = f.name
-        toxml(table, filename, **kwargs)
-        try:
-            actual = fromxml(filename, *check)
-            _compare(expected, actual)
-        except Exception as ex:
-            print('XML:', open(filename).read(), file=sys.stderr)
-            raise ex
+    toxml(table, filename, **kwargs)
+    try:
+        actual = fromxml(filename, *check)
+        _compare(expected, actual)
+    except Exception as ex:
+        print('XML:', open(filename).read(), file=sys.stderr)
+        raise ex
 
 
 _HEAD1 = (('foo', 'bar'),)