diff --git a/src/utils/lib.py b/src/utils/lib.py
index f084dde9..10babc85 100644
--- a/src/utils/lib.py
+++ b/src/utils/lib.py
@@ -765,7 +765,7 @@ class Timezoned:
         Return the start of the current month in the object's timezone
         """
         today = self.today
-        return today - datetime.timedelta(days=today.day)
+        return today - datetime.timedelta(days=(today.day - 1))
 
 
 def replace_multiple(format_string, mapping):