diff --git a/lib/components/settings/screens/timetable_period_screen.dart b/lib/components/settings/screens/timetable_period_screen.dart
index b949a93..4db3664 100644
--- a/lib/components/settings/screens/timetable_period_screen.dart
+++ b/lib/components/settings/screens/timetable_period_screen.dart
@@ -2,6 +2,7 @@ import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:timetable/constants/custom_times.dart';
+import 'package:timetable/extensions/time_of_day.dart';
 import 'package:timetable/helpers/time_management.dart';
 import 'package:timetable/provider/settings.dart';
 
@@ -108,7 +109,7 @@ class TimetablePeriodScreen extends ConsumerWidget {
                     return;
                   }
 
-                  if (isAfter(selectedTime, customEndTime)) {
+                  if (selectedTime.isAfter(customEndTime)) {
                     switchStartWithEndTime(selectedTime);
                     return;
                   }
@@ -134,7 +135,7 @@ class TimetablePeriodScreen extends ConsumerWidget {
                     return;
                   }
 
-                  if (isBefore(selectedTime, customStartTime)) {
+                  if (selectedTime.isBefore(customStartTime)) {
                     switchEndWithStartTime(selectedTime);
                     return;
                   }
diff --git a/lib/components/subject_management/subject_configs/time_config.dart b/lib/components/subject_management/subject_configs/time_config.dart
index 2f54ed8..a866b19 100644
--- a/lib/components/subject_management/subject_configs/time_config.dart
+++ b/lib/components/subject_management/subject_configs/time_config.dart
@@ -2,6 +2,7 @@ import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:timetable/components/widgets/act_chip.dart';
+import 'package:timetable/extensions/time_of_day.dart';
 import 'package:timetable/helpers/time_management.dart';
 import 'package:timetable/constants/custom_times.dart';
 import 'package:timetable/provider/settings.dart';
@@ -73,7 +74,7 @@ class TimeConfig extends ConsumerWidget {
     }
 
     void switchStartWithEndTime(TimeOfDay newTime) {
-      if (!isAfter(newTime, customEndTime)) {
+      if (!newTime.isAfter(customEndTime)) {
         final temp = endTime.value;
         endTime.value = newTime;
         startTime.value = temp;
@@ -83,7 +84,7 @@ class TimeConfig extends ConsumerWidget {
     }
 
     void switchEndWithStartTime(TimeOfDay newTime) {
-      if (!isBefore(newTime, customStartTime)) {
+      if (!newTime.isBefore(customStartTime)) {
         final temp = startTime.value;
         startTime.value = newTime;
         endTime.value = temp;
@@ -128,7 +129,7 @@ class TimeConfig extends ConsumerWidget {
 
             if (selectedTime == null) return;
 
-            if (isBefore(selectedTime, customStartTime)) {
+            if (selectedTime.isBefore(customStartTime)) {
               showInvalidTimePeriodDialog();
               return;
             }
@@ -138,7 +139,7 @@ class TimeConfig extends ConsumerWidget {
               return;
             }
 
-            if (isAfter(selectedTime, endTime.value)) {
+            if (selectedTime.isAfter(endTime.value)) {
               switchStartWithEndTime(selectedTime);
               return;
             }
@@ -165,7 +166,7 @@ class TimeConfig extends ConsumerWidget {
 
             if (selectedTime == null) return;
 
-            if (isAfter(selectedTime, customEndTime)) {
+            if (selectedTime.isAfter(customEndTime)) {
               showInvalidTimePeriodDialog();
               return;
             }
@@ -174,7 +175,7 @@ class TimeConfig extends ConsumerWidget {
               showInvalidEqualTimeDialog();
               return;
             }
-            if (isBefore(selectedTime, startTime.value)) {
+            if (selectedTime.isBefore(startTime.value)) {
               switchEndWithStartTime(selectedTime);
               return;
             }
diff --git a/lib/extensions/time_of_day.dart b/lib/extensions/time_of_day.dart
new file mode 100644
index 0000000..1095cae
--- /dev/null
+++ b/lib/extensions/time_of_day.dart
@@ -0,0 +1,23 @@
+import 'package:flutter/material.dart';
+
+extension TimeOfDayExtension on TimeOfDay {
+  bool isBefore(TimeOfDay other) {
+    if (hour < other.hour) {
+      return true;
+    } else if (hour == other.hour) {
+      return minute < other.minute;
+    } else {
+      return false;
+    }
+  }
+
+  bool isAfter(TimeOfDay other) {
+    if (hour > other.hour) {
+      return true;
+    } else if (hour == other.hour) {
+      return minute > other.minute;
+    } else {
+      return false;
+    }
+  }
+}
diff --git a/lib/helpers/time_management.dart b/lib/helpers/time_management.dart
index 00ac4e6..01a90d0 100644
--- a/lib/helpers/time_management.dart
+++ b/lib/helpers/time_management.dart
@@ -1,17 +1,5 @@
 import 'package:flutter/material.dart';
 
-/// check if time 1 is before time2
-bool isBefore(TimeOfDay time1, TimeOfDay time2) {
-  return (time1.hour < time2.hour) ||
-      (time1.hour == time2.hour && time1.minute < time2.minute);
-}
-
-/// check if time 1 is after time2
-bool isAfter(TimeOfDay time1, TimeOfDay time2) {
-  return (time1.hour > time2.hour) ||
-      (time1.hour == time2.hour && time1.minute > time2.minute);
-}
-
 /// returns a time picker
 ///
 /// initialEntryMode is set by default to [TimePickerEntryMode.input]