diff --git a/Wox/PublicAPIInstance.cs b/Wox/PublicAPIInstance.cs
index 0bb7621c2d..c828ff09d6 100644
--- a/Wox/PublicAPIInstance.cs
+++ b/Wox/PublicAPIInstance.cs
@@ -37,16 +37,12 @@ namespace Wox
 
                 if(e.KeyEventArgs.Key == Key.Back)
                 {
-                    if (null != BackKeyDownEvent)
+                    BackKeyDownEvent?.Invoke(new WoxKeyDownEventArgs
                     {
-                        BackKeyDownEvent(new WoxKeyDownEventArgs
-                        {
-                            Query = MainVM.QueryText,
-                            keyEventArgs = e.KeyEventArgs
-                        });
-                    }
+                        Query = MainVM.QueryText,
+                        keyEventArgs = e.KeyEventArgs
+                    });
                 }
-
             };
         }
 
diff --git a/Wox/ViewModel/BaseViewModel.cs b/Wox/ViewModel/BaseViewModel.cs
index 24757b0617..5f659f0956 100644
--- a/Wox/ViewModel/BaseViewModel.cs
+++ b/Wox/ViewModel/BaseViewModel.cs
@@ -9,10 +9,7 @@ namespace Wox.ViewModel
 
         protected void OnPropertyChanged(string propertyName)
         {
-            if (null != PropertyChanged)
-            {
-                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
-            }
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
         }
 
         public event PropertyChangedEventHandler PropertyChanged;
@@ -37,10 +34,7 @@ namespace Wox.ViewModel
 
         public virtual void Execute(object parameter)
         {
-            if (null != _action)
-            {
-                _action(parameter);
-            }
+            _action?.Invoke(parameter);
         }
     }
 }
diff --git a/Wox/ViewModel/MainViewModel.cs b/Wox/ViewModel/MainViewModel.cs
index 6d6c8cd1ea..40018aefed 100644
--- a/Wox/ViewModel/MainViewModel.cs
+++ b/Wox/ViewModel/MainViewModel.cs
@@ -287,7 +287,7 @@ namespace Wox.ViewModel
 
             ShiftEnterCommand = new RelayCommand(_ =>
             {
-                if (!IsContextMenuVisible && null != Results.SelectedResult)
+                if (!IsContextMenuVisible && Results.SelectedResult != null)
                 {
                     ShowContextMenu(Results.SelectedResult.RawResult);
                 }
@@ -295,7 +295,7 @@ namespace Wox.ViewModel
 
             OpenResultCommand = new RelayCommand(o =>
             {
-                if (null != o)
+                if (o != null)
                 {
                     var index = int.Parse(o.ToString());
                     Results.SelectResult(index);
diff --git a/Wox/ViewModel/ResultViewModel.cs b/Wox/ViewModel/ResultViewModel.cs
index 0ee8c98744..aa59b1e9f6 100644
--- a/Wox/ViewModel/ResultViewModel.cs
+++ b/Wox/ViewModel/ResultViewModel.cs
@@ -19,7 +19,7 @@ namespace Wox.ViewModel
 
         public ResultViewModel(Result result)
         {
-            if (null != result)
+            if (result != null)
             {
                 RawResult = result;
 
diff --git a/Wox/ViewModel/ResultsViewModel.cs b/Wox/ViewModel/ResultsViewModel.cs
index 77d89b5341..8e9f69d58d 100644
--- a/Wox/ViewModel/ResultsViewModel.cs
+++ b/Wox/ViewModel/ResultsViewModel.cs
@@ -35,16 +35,16 @@ namespace Wox.ViewModel
             }
             set
             {
-                if (null != value)
+                if (value != null)
                 {
-                    if (null != _selectedResult)
+                    if (_selectedResult != null)
                     {
                         _selectedResult.IsSelected = false;
                     }
 
                     _selectedResult = value;
 
-                    if (null != _selectedResult)
+                    if (_selectedResult != null)
                     {
                         _selectedResult.IsSelected = true;
                     }
@@ -106,7 +106,7 @@ namespace Wox.ViewModel
 
         public void SelectNextResult()
         {
-            if (null != SelectedResult)
+            if (SelectedResult != null)
             {
                 var index = Results.IndexOf(SelectedResult);
                 if (index == Results.Count - 1)
@@ -119,7 +119,7 @@ namespace Wox.ViewModel
 
         public void SelectPrevResult()
         {
-            if (null != SelectedResult)
+            if (SelectedResult != null)
             {
                 var index = Results.IndexOf(SelectedResult);
                 if (index == 0)
@@ -133,7 +133,7 @@ namespace Wox.ViewModel
         public void SelectNextPage()
         {
             var index = 0;
-            if (null != SelectedResult)
+            if (SelectedResult != null)
             {
                 index = Results.IndexOf(SelectedResult);
             }
@@ -148,7 +148,7 @@ namespace Wox.ViewModel
         public void SelectPrevPage()
         {
             var index = 0;
-            if (null != SelectedResult)
+            if (SelectedResult != null)
             {
                 index = Results.IndexOf(SelectedResult);
             }