diff --git a/Lib/unittest.py b/Lib/unittest.py
index 76b08d6c99f..d033936d2d0 100644
--- a/Lib/unittest.py
+++ b/Lib/unittest.py
@@ -560,8 +560,8 @@ class _WritelnDecorator:
     def __getattr__(self, attr):
         return getattr(self.stream,attr)
 
-    def writeln(self, *args):
-        if args: self.write(*args)
+    def writeln(self, arg=None):
+        if arg: self.write(arg)
         self.write('\n') # text-mode streams translate to \r\n if needed