diff --git a/CHANGELOG.md b/CHANGELOG.md
index c79798a3..55ffc59e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+## [1.12.4]
+* Default the `_selectedDay` state variable to be 1 when selecting the previous/next month from widget to ensure new date is valid for `_formatAsDateTime()` method (https://github.com/flutter/flutter/issues/123669 & https://github.com/macosui/macos_ui/pull/402)
+
 ## [1.12.3]
 * Added support for `routerConfig` to `MacosApp.router`. ([#388](https://github.com/macosui/macos_ui/issues/388))
 
diff --git a/lib/src/selectors/date_picker.dart b/lib/src/selectors/date_picker.dart
index f764394f..348fec85 100644
--- a/lib/src/selectors/date_picker.dart
+++ b/lib/src/selectors/date_picker.dart
@@ -354,9 +354,13 @@ class _MacosDatePickerState extends State<MacosDatePicker> {
                               setState(() {
                                 _selectedYear--;
                                 _selectedMonth = 12;
+                                _selectedDay = 1;
                               });
                             } else {
-                              setState(() => _selectedMonth--);
+                              setState(() {
+                                _selectedMonth--;
+                                _selectedDay = 1;
+                              });
                             }
                             widget.onDateChanged.call(_formatAsDateTime());
                           },
@@ -397,9 +401,13 @@ class _MacosDatePickerState extends State<MacosDatePicker> {
                               setState(() {
                                 _selectedYear++;
                                 _selectedMonth = 1;
+                                _selectedDay = 1;
                               });
                             } else {
-                              setState(() => _selectedMonth++);
+                              setState(() {
+                                _selectedMonth++;
+                                _selectedDay = 1;
+                              });
                             }
 
                             widget.onDateChanged.call(_formatAsDateTime());
diff --git a/pubspec.yaml b/pubspec.yaml
index 7e1d73a1..40ee143e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: macos_ui
 description: Flutter widgets and themes implementing the current macOS design language.
-version: 1.12.3
+version: 1.12.4
 homepage: "https://macosui.dev"
 repository: "https://github.com/GroovinChip/macos_ui"