diff --git a/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs b/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs
index d029295bd..52b7f44fe 100644
--- a/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs
+++ b/src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs
@@ -834,9 +834,6 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
         {
             using ImmutableArrayBuilder<StatementSyntax> setterStatements = ImmutableArrayBuilder<StatementSyntax>.Rent();
 
-            // Get the property type syntax
-            TypeSyntax propertyType = IdentifierName(propertyInfo.TypeNameWithNullabilityAnnotations);
-
             string getterFieldIdentifierName;
             ExpressionSyntax getterFieldExpression;
             ExpressionSyntax setterFieldExpression;
@@ -872,7 +869,7 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
                 // <PROPERTY_TYPE> __oldValue = <FIELD_EXPRESSIONS>;
                 setterStatements.Add(
                     LocalDeclarationStatement(
-                        VariableDeclaration(propertyType)
+                        VariableDeclaration(GetMaybeNullPropertyType(propertyInfo))
                         .AddVariables(
                             VariableDeclarator(Identifier("__oldValue"))
                             .WithInitializer(EqualsValueClause(setterFieldExpression)))));
@@ -1001,6 +998,9 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
                             Argument(LiteralExpression(SyntaxKind.StringLiteralExpression, Literal(propertyInfo.PropertyName))))));
             }
 
+            // Get the property type syntax
+            TypeSyntax propertyType = IdentifierName(propertyInfo.TypeNameWithNullabilityAnnotations);
+
             // Generate the inner setter block as follows:
             //
             // if (!global::System.Collections.Generic.EqualityComparer<<PROPERTY_TYPE>>.Default.Equals(<FIELD_EXPRESSION>, value))
@@ -1128,17 +1128,8 @@ public static ImmutableArray<MemberDeclarationSyntax> GetOnPropertyChangeMethods
                         Comment($"/// <remarks>This method is invoked right before the value of <see cref=\"{propertyInfo.PropertyName}\"/> is changed.</remarks>")), SyntaxKind.OpenBracketToken, TriviaList())))
                 .WithSemicolonToken(Token(SyntaxKind.SemicolonToken));
 
-            // Prepare the nullable type for the previous property value. This is needed because if the type is a reference
-            // type, the previous value might be null even if the property type is not nullable, as the first invocation would
-            // happen when the property is first set to some value that is not null (but the backing field would still be so).
-            // As a cheap way to check whether we need to add nullable, we can simply check whether the type name with nullability
-            // annotations ends with a '?'. If it doesn't and the type is a reference type, we add it. Otherwise, we keep it.
-            TypeSyntax oldValueTypeSyntax = propertyInfo.IsReferenceTypeOrUnconstraindTypeParameter switch
-            {
-                true when !propertyInfo.TypeNameWithNullabilityAnnotations.EndsWith("?")
-                    => IdentifierName($"{propertyInfo.TypeNameWithNullabilityAnnotations}?"),
-                _ => parameterType
-            };
+            // Get the type for the 'oldValue' parameter (which can be null on first invocation) 
+            TypeSyntax oldValueTypeSyntax = GetMaybeNullPropertyType(propertyInfo);
 
             // Construct the generated method as follows:
             //
@@ -1224,6 +1215,26 @@ public static ImmutableArray<MemberDeclarationSyntax> GetOnPropertyChangeMethods
                 onPropertyChanged2Declaration);
         }
 
+        /// <summary>
+        /// Gets the <see cref="TypeSyntax"/> for the type of a given property, when it can possibly be <see langword="null"/>.
+        /// </summary>
+        /// <param name="propertyInfo">The input <see cref="PropertyInfo"/> instance to process.</param>
+        /// <returns>The type of a given property, when it can possibly be <see langword="null"/></returns>
+        private static TypeSyntax GetMaybeNullPropertyType(PropertyInfo propertyInfo)
+        {
+            // Prepare the nullable type for the previous property value. This is needed because if the type is a reference
+            // type, the previous value might be null even if the property type is not nullable, as the first invocation would
+            // happen when the property is first set to some value that is not null (but the backing field would still be so).
+            // As a cheap way to check whether we need to add nullable, we can simply check whether the type name with nullability
+            // annotations ends with a '?'. If it doesn't and the type is a reference type, we add it. Otherwise, we keep it.
+            return propertyInfo.IsReferenceTypeOrUnconstraindTypeParameter switch
+            {
+                true when !propertyInfo.TypeNameWithNullabilityAnnotations.EndsWith("?")
+                    => IdentifierName($"{propertyInfo.TypeNameWithNullabilityAnnotations}?"),
+                _ => IdentifierName(propertyInfo.TypeNameWithNullabilityAnnotations)
+            };
+        }
+
         /// <summary>
         /// Gets a <see cref="CompilationUnitSyntax"/> instance with the cached args of a specified type.
         /// </summary>
diff --git a/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs b/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs
index c3e48fba6..a1e954d85 100644
--- a/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs
+++ b/tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsCodegen.cs
@@ -2301,7 +2301,7 @@ partial class MyViewModel : ObservableObject
                 [ObservableProperty]
                 double @object;
 
-                partial void OnObjectChanged(object oldValue, object NewValue)
+                partial void OnObjectChanged(double oldValue, double NewValue)
                 {
                 }
             }
@@ -3018,6 +3018,284 @@ public string Name
         VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, ("MyApp.MyViewModel.g.cs", result));
     }
 
+    [TestMethod]
+    public void ObservableProperty_NotNullableProperty_OfReferenceType_WithChangedMethods()
+    {
+        string source = """
+            using CommunityToolkit.Mvvm.ComponentModel;
+
+            namespace MyApp;
+            
+            partial class MyViewModel : ObservableObject
+            {
+                [ObservableProperty]
+                string name;
+
+                partial void OnNameChanged(string? oldValue, string NewValue)
+                {
+                }
+            }
+            """;
+
+#if NET6_0_OR_GREATER
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel
+                {
+                    /// <inheritdoc cref="name"/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    public string Name
+                    {
+                        get => name;
+                        [global::System.Diagnostics.CodeAnalysis.MemberNotNull("name")]
+                        set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<string>.Default.Equals(name, value))
+                            {
+                                string? __oldValue = name;
+                                OnNameChanging(value);
+                                OnNameChanging(__oldValue, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.Name);
+                                name = value;
+                                OnNameChanged(value);
+                                OnNameChanged(__oldValue, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.Name);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanging(string value);
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanging(string? oldValue, string newValue);
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanged(string value);
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanged(string? oldValue, string newValue);
+                }
+            }
+            """;
+#else
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel
+                {
+                    /// <inheritdoc cref="name"/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    public string Name
+                    {
+                        get => name;
+                        set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<string>.Default.Equals(name, value))
+                            {
+                                string? __oldValue = name;
+                                OnNameChanging(value);
+                                OnNameChanging(__oldValue, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.Name);
+                                name = value;
+                                OnNameChanged(value);
+                                OnNameChanged(__oldValue, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.Name);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanging(string value);
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanging(string? oldValue, string newValue);
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanged(string value);
+                    /// <summary>Executes the logic for when <see cref="Name"/> 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="Name"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnNameChanged(string? oldValue, string newValue);
+                }
+            }
+            """;
+#endif
+
+        VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, ("MyApp.MyViewModel.g.cs", result));
+    }
+
+    [TestMethod]
+    public void ObservableProperty_NotNullableProperty_OfUnconstrainedGenericType_WithChangedMethods()
+    {
+        string source = """
+            using CommunityToolkit.Mvvm.ComponentModel;
+
+            namespace MyApp;
+            
+            partial class MyViewModel<T> : ObservableObject
+            {
+                [ObservableProperty]
+                T value;
+
+                partial void OnValueChanged(T? oldValue, T NewValue)
+                {
+                }
+            }
+            """;
+
+#if NET6_0_OR_GREATER
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel<T>
+                {
+                    /// <inheritdoc cref="value"/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    public T Value
+                    {
+                        get => value;
+                        [global::System.Diagnostics.CodeAnalysis.MemberNotNull("value")]
+                        set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<T>.Default.Equals(this.value, value))
+                            {
+                                T? __oldValue = this.value;
+                                OnValueChanging(value);
+                                OnValueChanging(__oldValue, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.Value);
+                                this.value = value;
+                                OnValueChanged(value);
+                                OnValueChanged(__oldValue, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.Value);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanging(T value);
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanging(T? oldValue, T newValue);
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanged(T value);
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanged(T? oldValue, T newValue);
+                }
+            }
+            """;
+#else
+        string result = """
+            // <auto-generated/>
+            #pragma warning disable
+            #nullable enable
+            namespace MyApp
+            {
+                /// <inheritdoc/>
+                partial class MyViewModel<T>
+                {
+                    /// <inheritdoc cref="value"/>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+                    public T Value
+                    {
+                        get => value;
+                        set
+                        {
+                            if (!global::System.Collections.Generic.EqualityComparer<T>.Default.Equals(this.value, value))
+                            {
+                                T? __oldValue = this.value;
+                                OnValueChanging(value);
+                                OnValueChanging(__oldValue, value);
+                                OnPropertyChanging(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangingArgs.Value);
+                                this.value = value;
+                                OnValueChanged(value);
+                                OnValueChanged(__oldValue, value);
+                                OnPropertyChanged(global::CommunityToolkit.Mvvm.ComponentModel.__Internals.__KnownINotifyPropertyChangedArgs.Value);
+                            }
+                        }
+                    }
+
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanging(T value);
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanging(T? oldValue, T newValue);
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanged(T value);
+                    /// <summary>Executes the logic for when <see cref="Value"/> 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="Value"/> is changed.</remarks>
+                    [global::System.CodeDom.Compiler.GeneratedCode("CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator", <ASSEMBLY_VERSION>)]
+                    partial void OnValueChanged(T? oldValue, T newValue);
+                }
+            }
+            """;
+#endif
+
+        VerifyGenerateSources(source, new[] { new ObservablePropertyGenerator() }, ("MyApp.MyViewModel`1.g.cs", result));
+    }
+
     /// <summary>
     /// Generates the requested sources
     /// </summary>