diff --git a/README.md b/README.md
index d6e3b60..a47c0dd 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ optional arguments:
 
 Example
 ```
-$ elicznik freddy@example.com secretpassword 10.7.2021
+$ elicznik freddy@example.com secretpassword 2021-07-10
 timestamp              consumed    produced
 -------------------  ----------  ----------
 2021-07-03 01:00:00       0.116       0
diff --git a/src/elicznik/__main__.py b/src/elicznik/__main__.py
index e1079cf..79696b6 100644
--- a/src/elicznik/__main__.py
+++ b/src/elicznik/__main__.py
@@ -22,7 +22,7 @@ def main():
     parser.add_argument(
         "date",
         nargs="?",
-        type=lambda arg: datetime.datetime.strptime(arg, "%d.%m.%Y").date(),
+        type=datetime.date.fromisoformat,
         default=datetime.date.today() - datetime.timedelta(days=1),
         help="Date of data to be retrieved",
     )