diff --git a/lib/spack/spack/test/cmd/flake8.py b/lib/spack/spack/test/cmd/flake8.py
index b95db93364..6cad6950ba 100644
--- a/lib/spack/spack/test/cmd/flake8.py
+++ b/lib/spack/spack/test/cmd/flake8.py
@@ -45,7 +45,7 @@ def flake8_package():
 
 
 def test_changed_files(parser, flake8_package):
-    args = parser.parse_args()
+    args = parser.parse_args([])
 
     # changed_files returns file paths relative to the root
     # directory of Spack. Convert to absolute file paths.