diff --git a/extensions/birthday.py b/extensions/birthday.py
index 87eeac8b..65b83568 100644
--- a/extensions/birthday.py
+++ b/extensions/birthday.py
@@ -728,8 +728,7 @@ async def birthday_list(self, ctx: ipy.SlashContext):
                 day_from = i + 1
                 day_limit = i + 7
                 # use last day of the month if the day limit exceeds
-                mnend = datetime(today.year, today.month +
-                                 1, 1) - timedelta(days=1)
+                mnend = today.replace(day=1, month=today.month % 12 + 1) - timedelta(days=1)
                 if day_limit > mnend.day:
                     day_limit = mnend.day
                 index = f"{day_from} to {day_limit}" if day_from < day_limit else f"{day_from}"