diff --git a/src/AdvancedCalculator/ViewModels/MainViewModel.cs b/src/AdvancedCalculator/ViewModels/MainViewModel.cs
index 011b3b7..222de45 100644
--- a/src/AdvancedCalculator/ViewModels/MainViewModel.cs
+++ b/src/AdvancedCalculator/ViewModels/MainViewModel.cs
@@ -5,6 +5,7 @@ using CommunityToolkit.Mvvm.Input;
 using AdvancedCalculator.Models;
 using AdvancedCalculator.Services;
 using CSMic;
+using System;
 
 namespace AdvancedCalculator.ViewModels;
 
@@ -47,7 +48,7 @@ public partial class MainViewModel : ViewModelBase
     [RelayCommand]
     private void InsertVariable(VariableItem variableItem)
     {
-        if(variableItem == null) return;
+        if (variableItem == null) return;
         if (string.IsNullOrWhiteSpace(variableItem.VariableName))
             return;
         InsertToken(variableItem.VariableName);
@@ -56,7 +57,7 @@ public partial class MainViewModel : ViewModelBase
     [RelayCommand]
     private void InsertFunction(FunctionDefinitionItem functionDefintionItem)
     {
-        if(functionDefintionItem == null) return;
+        if (functionDefintionItem == null) return;
         if (string.IsNullOrWhiteSpace(functionDefintionItem.FunctionName))
             return;
         InsertToken(functionDefintionItem.FunctionName + "()");