diff --git a/Pilz.UI/Extensions/DialogResultExtensions.cs b/Pilz.UI/Extensions/DialogResultExtensions.cs
index 9292f94..f754b47 100644
--- a/Pilz.UI/Extensions/DialogResultExtensions.cs
+++ b/Pilz.UI/Extensions/DialogResultExtensions.cs
@@ -1,54 +1,31 @@
-namespace Pilz.UI.Extensions;
+using System.Diagnostics.CodeAnalysis;
+
+namespace Pilz.UI.Extensions;
 
 public static class DialogResultExtensions
 {
-    public static bool Is(this DialogResult @this, DialogResult result)
+    public static bool Is([NotNullWhen(true)] this DialogResult? @this, DialogResult result)
     {
         return @this == result;
     }
     
-    public static bool IsNot(this DialogResult @this, DialogResult result)
-    {
-        return @this != result;
-    }
-    
-    public static bool Is(this DialogResult @this, params DialogResult[] results)
+    public static bool Is([NotNullWhen(true)] this DialogResult? @this, params DialogResult[] results)
     {
         return results.Any(result => @this == result);
     }
-    
-    public static bool IsNot(this DialogResult @this, params DialogResult[] results)
-    {
-        return results.All(result => @this != result);
-    }
 
-    public static bool IsOk(this DialogResult @this)
+    public static bool IsOk([NotNullWhen(true)] this DialogResult? @this)
     {
         return @this == DialogResult.OK;
     }
-    
-    public static bool IsNotOk(this DialogResult @this)
-    {
-        return @this != DialogResult.OK;
-    }
 
-    public static bool IsYes(this DialogResult @this)
+    public static bool IsYes([NotNullWhen(true)] this DialogResult? @this)
     {
         return @this == DialogResult.Yes;
     }
     
-    public static bool IsNotYes(this DialogResult @this)
-    {
-        return @this != DialogResult.Yes;
-    }
-    
-    public static bool IsCancel(this DialogResult @this)
+    public static bool IsCancel([NotNullWhen(true)] this DialogResult? @this)
     {
         return @this == DialogResult.Cancel;
     }
-    
-    public static bool IsNotCancel(this DialogResult @this)
-    {
-        return @this != DialogResult.Cancel;
-    }
 }