diff --git a/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs b/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs
index 620477b6cd..a9fc18474c 100644
--- a/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs
+++ b/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs
@@ -515,7 +515,7 @@ namespace Avalonia.Markup.Parsers
 
             public string Value { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is AttachedPropertySyntax syntax
                     && syntax.Xmlns == Xmlns
diff --git a/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs b/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs
index e2d6570790..1b7ee9025e 100644
--- a/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs
+++ b/src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs
@@ -119,7 +119,7 @@ namespace Avalonia.Markup.Parsers
                         }
 
                         {
-                            object typedValue;
+                            object? typedValue;
 
                             if (TypeUtilities.TryConvert(
                                     targetAttachedProperty.PropertyType,