diff --git a/mesonbuild/rewriter.py b/mesonbuild/rewriter.py
index 626551014..680eed1f8 100644
--- a/mesonbuild/rewriter.py
+++ b/mesonbuild/rewriter.py
@@ -25,7 +25,7 @@ class RewriterException(MesonException):
 
 # Note: when adding arguments, please also add them to the completion
 # scripts in $MESONSRC/data/shell-completions/
-def add_arguments(parser, formatter=None):
+def add_arguments(parser, formatter):
     parser.add_argument('-s', '--sourcedir', type=str, default='.', metavar='SRCDIR', help='Path to source directory.')
     parser.add_argument('-V', '--verbose', action='store_true', default=False, help='Enable verbose output')
     parser.add_argument('-S', '--skip-errors', dest='skip', action='store_true', default=False, help='Skip errors instead of aborting')