diff --git a/tests/test_Configuration.py b/tests/test_Configuration.py
index 4c85edbe40c8640b3dc15e843bf21ec234286843..7529a9f764774a0a297e6e3ca9c76523b99e22c6 100644
--- a/tests/test_Configuration.py
+++ b/tests/test_Configuration.py
@@ -128,3 +128,12 @@ def test_bad_date_parsing(date_s):
         pass
     else:
         assert not config.args.date, "date parsed from {!r}".format(date_s)
+
+def test_ambiguous_arglist_failure():
+    try:
+        # It's ambiguous if "2" is "the 2nd" or "2 EUR".
+        config = config_from(os.devnull, ['historical', '2', 'eur'])
+    except SystemExit:
+        pass
+    else:
+        assert not config.args, "ambiguous args parsed"