diff --git a/example/lib/main.dart b/example/lib/main.dart
index 755bb55..81a613d 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -190,7 +190,8 @@ class MySampleState extends State<MySample> {
                           style: ElevatedButton.styleFrom(
                             shape: RoundedRectangleBorder(
                               borderRadius: BorderRadius.circular(8.0),
-                            ), backgroundColor: const Color(0xff1b447b),
+                            ),
+                            backgroundColor: const Color(0xff1b447b),
                           ),
                           child: Container(
                             margin: const EdgeInsets.all(12),
diff --git a/lib/credit_card_form.dart b/lib/credit_card_form.dart
index f9235f4..ee4a9d0 100644
--- a/lib/credit_card_form.dart
+++ b/lib/credit_card_form.dart
@@ -111,7 +111,7 @@ class _CreditCardFormState extends State<CreditCardForm> {
     super.initState();
 
     createCreditCardModel();
-      
+
     _cardNumberController.text = widget.cardNumber;
     _expiryDateController.text = widget.expiryDate;
     _cardHolderNameController.text = widget.cardHolderName;
@@ -245,8 +245,11 @@ class _CreditCardFormState extends State<CreditCardForm> {
                           final List<String> date = value.split(RegExp(r'/'));
                           final int month = int.parse(date.first);
                           final int year = int.parse('20${date.last}');
-                          final int lastDayOfMonth =  month < 12 ? DateTime(year, month + 1, 0).day : DateTime(year + 1, 1, 0).day;
-                          final DateTime cardDate = DateTime(year, month, lastDayOfMonth,23,59,59,999);
+                          final int lastDayOfMonth = month < 12
+                              ? DateTime(year, month + 1, 0).day
+                              : DateTime(year + 1, 1, 0).day;
+                          final DateTime cardDate = DateTime(
+                              year, month, lastDayOfMonth, 23, 59, 59, 999);
 
                           if (cardDate.isBefore(now) ||
                               month > 12 ||