diff --git a/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/TypedConstantInfo.cs b/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/TypedConstantInfo.cs
index 4538afaf..da13fd42 100644
--- a/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/TypedConstantInfo.cs
+++ b/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/TypedConstantInfo.cs
@@ -134,10 +134,9 @@ public sealed record Enum(string TypeName, object Value) : TypedConstantInfo
         /// <inheritdoc/>
         public override ExpressionSyntax GetSyntax()
         {
-            return
-                CastExpression(
-                    IdentifierName(TypeName),
-                    LiteralExpression(SyntaxKind.NumericLiteralExpression, ParseToken(Value.ToString())));
+            // We let Roslyn parse the value expression, so that it can automatically handle both positive and negative values. This
+            // is needed because negative values have a different syntax tree (UnaryMinuxExpression holding the numeric expression).
+            return CastExpression(IdentifierName(TypeName), ParseExpression(Value.ToString()));
         }
     }
 
diff --git a/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs b/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs
index 0062d61d..6edc38b5 100644
--- a/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs
+++ b/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs
@@ -1283,6 +1283,278 @@ partial class MyViewModel
         VerifyGenerateSources(source, new[] { new RelayCommandGenerator() }, ("MyApp.MyViewModel.Test.g.cs", result));
     }
 
+    // See https://github.com/CommunityToolkit/dotnet/issues/681
+    [TestMethod]
+    public void ObservablePropertyWithForwardedAttributesWithEnumWithNegativeValue_WorksCorrectly()
+    {
+        string source = """
+            using System.ComponentModel;
+            using CommunityToolkit.Mvvm.ComponentModel;
+
+            #nullable enable
+
+            namespace MyApp;
+            
+            partial class MyViewModel : ObservableObject
+            {
+                [ObservableProperty]
+                [property: DefaultValue(NegativeEnum1.Problem)]
+                [property: DefaultValue(NegativeEnum2.Problem)]
+                [property: DefaultValue(NegativeEnum3.Problem)]
+                [property: DefaultValue(NegativeEnum4.Problem)]
+                private object? a;
+            }
+
+            public class DefaultValueAttribute : Attribute
+            {
+                public DefaultValueAttribute(object value)
+                {
+                }
+            }
+
+            public enum NegativeEnum1
+            {
+                Problem = -1073741824,
+                OK = 0
+            }
+
+            public enum NegativeEnum2 : long
+            {
+                Problem = long.MinValue,
+                OK = 0
+            }
+
+            public enum NegativeEnum3 : short
+            {
+                Problem = -1234,
+                OK = 0
+            }
+
+            public enum NegativeEnum4 : sbyte
+            {
+                Problem = -1,
+                OK = 0
+            }
+            """;
+
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel
+                {
+                    /// <inheritdoc cref="a"/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)-1073741824)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)-9223372036854775808)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)-1234)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)-1)]
+                    public object? A
+                    {
+                        get => a;
+                        set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<object?>.Default.Equals(a, value))
+                            {
+                                OnAChanging(value);
+                                OnAChanging(default, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.A);
+                                a = value;
+                                OnAChanged(value);
+                                OnAChanged(default, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.A);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="A"/> is changing.</summary>
+                    /// <param name="value">The new property value being set.</param>
+                    /// <remarks>This method is invoked right before the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanging(object? value);
+                    /// <summary>Executes the logic for when <see cref="A"/> is changing.</summary>
+                    /// <param name="oldValue">The previous property value that is being replaced.</param>
+                    /// <param name="newValue">The new property value being set.</param>
+                    /// <remarks>This method is invoked right before the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanging(object? oldValue, object? newValue);
+                    /// <summary>Executes the logic for when <see cref="A"/> just changed.</summary>
+                    /// <param name="value">The new property value that was set.</param>
+                    /// <remarks>This method is invoked right after the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanged(object? value);
+                    /// <summary>Executes the logic for when <see cref="A"/> just changed.</summary>
+                    /// <param name="oldValue">The previous property value that was replaced.</param>
+                    /// <param name="newValue">The new property value that was set.</param>
+                    /// <remarks>This method is invoked right after the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanged(object? oldValue, object? newValue);
+                }
+            }
+            """;
+
+        VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, ("MyApp.MyViewModel.g.cs", result));
+    }
+
+    [TestMethod]
+    public void ObservablePropertyWithForwardedAttributesWithEnumWithCombinedValues_WorksCorrectly()
+    {
+        string source = """
+            using System.ComponentModel;
+            using CommunityToolkit.Mvvm.ComponentModel;
+
+            #nullable enable
+
+            namespace MyApp;
+            
+            partial class MyViewModel : ObservableObject
+            {
+                [ObservableProperty]
+                [property: DefaultValue(NegativeEnum1.A)]
+                [property: DefaultValue(NegativeEnum1.B)]
+                [property: DefaultValue((NegativeEnum1)42)]
+                [property: DefaultValue((NegativeEnum1)OtherClass.MyNumber)]
+                [property: DefaultValue(OtherClass.MyEnumValue)]
+                [property: DefaultValue(NegativeEnum2.A)]
+                [property: DefaultValue(NegativeEnum2.B)]
+                [property: DefaultValue((NegativeEnum2)42)]
+                [property: DefaultValue((NegativeEnum2)OtherClass.MyNumber)]
+                [property: DefaultValue((NegativeEnum2)(int)OtherClass.MyEnumValue)]
+                [property: DefaultValue(NegativeEnum3.A)]
+                [property: DefaultValue(NegativeEnum3.B)]
+                [property: DefaultValue((NegativeEnum3)42)]
+                [property: DefaultValue((NegativeEnum3)OtherClass.MyNumber)]
+                [property: DefaultValue((NegativeEnum3)(int)OtherClass.MyEnumValue)]
+                [property: DefaultValue(NegativeEnum4.A)]
+                [property: DefaultValue(NegativeEnum4.B)]
+                [property: DefaultValue((NegativeEnum4)42)]
+                [property: DefaultValue((NegativeEnum4)unchecked((sbyte)OtherClass.MyNumber))]
+                [property: DefaultValue((NegativeEnum4)(int)OtherClass.MyEnumValue)]
+                private object? a;
+            }
+
+            public static class OtherClass
+            {
+                public const int MyNumber = 456;
+                public const NegativeEnum1 MyEnumValue = NegativeEnum1.C;
+            }
+
+            public class DefaultValueAttribute : Attribute
+            {
+                public DefaultValueAttribute(object value)
+                {
+                }
+            }
+
+            public enum NegativeEnum1
+            {
+                A = 0,
+                B = -1073741824,
+                C = 123
+            }
+
+            public enum NegativeEnum2 : long
+            {
+                A = 0,
+                B = long.MinValue
+            }
+
+            public enum NegativeEnum3 : short
+            {
+                A = 1,
+                B = -1234
+            }
+
+            public enum NegativeEnum4 : sbyte
+            {
+                A = 1,
+                B = -1
+            }
+            """;
+
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel
+                {
+                    /// <inheritdoc cref="a"/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)0)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)-1073741824)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)42)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)456)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)123)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)0)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)-9223372036854775808)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)42)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)456)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)123)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)1)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)-1234)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)42)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)456)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)123)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)1)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)-1)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)42)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)-56)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)123)]
+                    public object? A
+                    {
+                        get => a;
+                        set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<object?>.Default.Equals(a, value))
+                            {
+                                OnAChanging(value);
+                                OnAChanging(default, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.A);
+                                a = value;
+                                OnAChanged(value);
+                                OnAChanged(default, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.A);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="A"/> is changing.</summary>
+                    /// <param name="value">The new property value being set.</param>
+                    /// <remarks>This method is invoked right before the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanging(object? value);
+                    /// <summary>Executes the logic for when <see cref="A"/> is changing.</summary>
+                    /// <param name="oldValue">The previous property value that is being replaced.</param>
+                    /// <param name="newValue">The new property value being set.</param>
+                    /// <remarks>This method is invoked right before the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanging(object? oldValue, object? newValue);
+                    /// <summary>Executes the logic for when <see cref="A"/> just changed.</summary>
+                    /// <param name="value">The new property value that was set.</param>
+                    /// <remarks>This method is invoked right after the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanged(object? value);
+                    /// <summary>Executes the logic for when <see cref="A"/> just changed.</summary>
+                    /// <param name="oldValue">The previous property value that was replaced.</param>
+                    /// <param name="newValue">The new property value that was set.</param>
+                    /// <remarks>This method is invoked right after the value of <see cref="A"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", "8.2.0.0")]
+                    partial void OnAChanged(object? oldValue, object? newValue);
+                }
+            }
+            """;
+
+        VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, ("MyApp.MyViewModel.g.cs", result));
+    }
+
     // See https://github.com/CommunityToolkit/dotnet/issues/632
     [TestMethod]
     public void RelayCommandMethodWithPartialDeclarations_TriggersCorrectly()
@@ -1450,6 +1722,96 @@ partial class MyViewModel
         VerifyGenerateSources(source, new[] { new RelayCommandGenerator() }, ("MyApp.MyViewModel.Test1.g.cs", result1), ("MyApp.MyViewModel.Test2.g.cs", result2));
     }
 
+    // See https://github.com/CommunityToolkit/dotnet/issues/681
+    [TestMethod]
+    public void RelayCommandMethodWithForwardedAttributesWithEnumValues_WorksCorrectly()
+    {
+        string source = """
+            using CommunityToolkit.Mvvm.Input;
+
+            #nullable enable
+
+            namespace MyApp;
+            
+            partial class MyViewModel
+            {
+                [RelayCommand]
+                [field: DefaultValue(NegativeEnum1.Problem)]
+                [field: DefaultValue(NegativeEnum2.Problem)]
+                [field: DefaultValue(NegativeEnum3.Problem)]
+                [field: DefaultValue(NegativeEnum4.Problem)]
+                [property: DefaultValue(NegativeEnum1.Problem)]
+                [property: DefaultValue(NegativeEnum2.Problem)]
+                [property: DefaultValue(NegativeEnum3.Problem)]
+                [property: DefaultValue(NegativeEnum4.Problem)]
+                private void Test()
+                {
+                }
+            }
+
+            public class DefaultValueAttribute : Attribute
+            {
+                public DefaultValueAttribute(object value)
+                {
+                }
+            }
+
+            public enum NegativeEnum1
+            {
+                Problem = -1073741824,
+                OK = 0
+            }
+
+            public enum NegativeEnum2 : long
+            {
+                Problem = long.MinValue,
+                OK = 0
+            }
+
+            public enum NegativeEnum3 : short
+            {
+                Problem = -1234,
+                OK = 0
+            }
+
+            public enum NegativeEnum4 : sbyte
+            {
+                Problem = -1,
+                OK = 0
+            }
+            """;
+
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel
+                {
+                    /// <summary>The backing field for <see cref="TestCommand"/>.</summary>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.RelayCommandGenerator", "8.2.0.0")]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)-1073741824)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)-9223372036854775808)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)-1234)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)-1)]
+                    private global::CommunityToolkit.Mvvm.Input.RelayCommand? testCommand;
+                    /// <summary>Gets an <see cref="global::CommunityToolkit.Mvvm.Input.IRelayCommand"/> instance wrapping <see cref="Test"/>.</summary>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.RelayCommandGenerator", "8.2.0.0")]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum1)-1073741824)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum2)-9223372036854775808)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum3)-1234)]
+                    [global::MyApp.DefaultValueAttribute((global::MyApp.NegativeEnum4)-1)]
+                    public global::CommunityToolkit.Mvvm.Input.IRelayCommand TestCommand => testCommand ??= new global::CommunityToolkit.Mvvm.Input.RelayCommand(new global::System.Action(Test));
+                }
+            }
+            """;
+
+        VerifyGenerateSources(source, new[] { new RelayCommandGenerator() }, ("MyApp.MyViewModel.Test.g.cs", result));
+    }
+
     [TestMethod]
     public void ObservablePropertyWithinGenericAndNestedTypes()
     {