diff --git a/lib/main.dart b/lib/main.dart
index babf2ba..7825e99 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -16,11 +16,11 @@ class MainApp extends StatelessWidget {
     const inputHeight = 50.0;
 
     const recurrenceValues = <DropdownMenuEntry>[
-      DropdownMenuEntry(value: "D", label: "Daily"),
-      DropdownMenuEntry(value: "W", label: "Weekly"),
-      DropdownMenuEntry(value: "B", label: "Biweekly"),
-      DropdownMenuEntry(value: "M", label: "Monthly"),
-      DropdownMenuEntry(value: "Y", label: "Yearly")
+      DropdownMenuEntry(value: Recurrence.daily, label: "Daily"),
+      DropdownMenuEntry(value: Recurrence.weekly, label: "Weekly"),
+      DropdownMenuEntry(value: Recurrence.biweekly, label: "Biweekly"),
+      DropdownMenuEntry(value: Recurrence.montly, label: "Monthly"),
+      DropdownMenuEntry(value: Recurrence.yearly, label: "Yearly")
     ];
 
     var cost;
@@ -66,10 +66,19 @@ class MainApp extends StatelessWidget {
   }
 }
 
+// https://www.tutorialspoint.com/dart_programming/dart_programming_enumeration.htm
+enum Recurrence {
+  daily,
+  weekly,
+  biweekly,
+  montly,
+  yearly
+}
+
 class Expense {
   String name;
   double cost;
-  Enum recurrence;
+  Recurrence recurrence;
   String description;
 
   Expense(this.name, this.cost, this.recurrence, this.description);