diff --git a/CHANGELOG.md b/CHANGELOG.md
index bfef439bc2..4882062564 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Castle Core Changelog
 
+## Unreleased
+
+Bugfixes:
+- Nested custom attribute types do not get replicated (@stakx, #638)
+
 ## 5.1.0 (2022-08-02)
 
 Enhancements:
diff --git a/src/Castle.Core.Tests/DynamicProxy.Tests/ClassWithAttributesTestCase.cs b/src/Castle.Core.Tests/DynamicProxy.Tests/ClassWithAttributesTestCase.cs
index 0acfa572c5..fd8d893eda 100644
--- a/src/Castle.Core.Tests/DynamicProxy.Tests/ClassWithAttributesTestCase.cs
+++ b/src/Castle.Core.Tests/DynamicProxy.Tests/ClassWithAttributesTestCase.cs
@@ -112,6 +112,53 @@ public void EnsureProxyHasAttributesOnGenericArgument()
 			Assert.IsTrue(nameProperty.IsDefined(typeof(NonInheritableAttribute), false));
 		}
 
+		[Test]
+		public void EnsureProxyHasNestedAttributesOnClassAndMethods()
+		{
+			var instance = (HasNestedNonInheritableAttribute)generator.CreateClassProxy(typeof(HasNestedNonInheritableAttribute), new StandardInterceptor());
+
+			object[] attributes = instance.GetType().GetCustomAttributes(typeof(Nested.NonInheritableAttribute), false).ToArray();
+			Assert.AreEqual(1, attributes.Length);
+			Assert.IsInstanceOf(typeof(Nested.NonInheritableAttribute), attributes[0]);
+
+			attributes = instance.GetType().GetMethod("OnMethod").GetCustomAttributes(typeof(Nested.NonInheritableAttribute), false).ToArray();
+			Assert.AreEqual(1, attributes.Length);
+			Assert.IsInstanceOf(typeof(Nested.NonInheritableAttribute), attributes[0]);
+		}
+
+		[Test]
+		public void EnsureProxyHasNestedAttributesOnProperties()
+		{
+			var proxy = generator.CreateClassProxy<HasNestedNonInheritableAttribute>();
+			var nameProperty = proxy.GetType().GetProperty("OnProperty");
+			Assert.IsTrue(nameProperty.IsDefined(typeof(Nested.NonInheritableAttribute), false));
+		}
+
+		[Test, Ignore("Not supported. Is it possible? There seems to be no API to allow that.")]
+		public void EnsureProxyHasNestedAttributesOnOnReturn()
+		{
+			var proxy = generator.CreateClassProxy<HasNestedNonInheritableAttribute>();
+			var nameProperty = proxy.GetType().GetMethod("OnReturn").ReturnParameter;
+			Assert.IsTrue(nameProperty.IsDefined(typeof(Nested.NonInheritableAttribute), false));
+		}
+
+		[Test]
+		public void EnsureProxyHasNestedAttributesOnParameter()
+		{
+			var proxy = generator.CreateClassProxy<HasNestedNonInheritableAttribute>();
+			ParameterInfo nameProperty = proxy.GetType().GetMethod("OnParameter").GetParameters().Single();
+			Assert.IsTrue(nameProperty.IsDefined(typeof(Nested.NonInheritableAttribute), false));
+		}
+
+		[Test]
+		[Platform(Exclude = "Mono", Reason = "Mono does not currently emit custom attributes on generic type parameters of methods. See https://github.com/mono/mono/issues/8512.")]
+		public void EnsureProxyHasNestedAttributesOnGenericArgument()
+		{
+			var proxy = generator.CreateClassProxy<HasNestedNonInheritableAttribute>();
+			var nameProperty = proxy.GetType().GetMethod("OnGenericArgument").GetGenericArguments().Single();
+			Assert.IsTrue(nameProperty.IsDefined(typeof(Nested.NonInheritableAttribute), false));
+		}
+
 		[Test]
 		public void Can_proxy_type_with_non_inheritable_attribute_depending_on_array_of_something_via_property()
 		{
diff --git a/src/Castle.Core.Tests/DynamicProxy.Tests/Classes/HasNestedNonInheritableAttribute.cs b/src/Castle.Core.Tests/DynamicProxy.Tests/Classes/HasNestedNonInheritableAttribute.cs
new file mode 100644
index 0000000000..57c922ab94
--- /dev/null
+++ b/src/Castle.Core.Tests/DynamicProxy.Tests/Classes/HasNestedNonInheritableAttribute.cs
@@ -0,0 +1,45 @@
+// Copyright 2004-2022 Castle Project - http://www.castleproject.org/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace Castle.DynamicProxy.Tests.Classes
+{
+	[Nested.NonInheritable]
+	public class HasNestedNonInheritableAttribute
+	{
+		[Nested.NonInheritable]
+		public virtual void OnMethod()
+		{
+		}
+
+		[Nested.NonInheritable]
+		public virtual string OnProperty
+		{
+			get; set;
+		}
+
+		[return: Nested.NonInheritable]
+		public virtual int OnReturn()
+		{
+			return 1;
+		}
+
+		public virtual void OnParameter([Nested.NonInheritable] int arg)
+		{
+		}
+
+		public virtual void OnGenericArgument<[Nested.NonInheritable] T>()
+		{
+		}
+	}
+}
diff --git a/src/Castle.Core.Tests/DynamicProxy.Tests/Classes/NestedNonInheritableAttribute.cs b/src/Castle.Core.Tests/DynamicProxy.Tests/Classes/NestedNonInheritableAttribute.cs
new file mode 100644
index 0000000000..a0ebf7e238
--- /dev/null
+++ b/src/Castle.Core.Tests/DynamicProxy.Tests/Classes/NestedNonInheritableAttribute.cs
@@ -0,0 +1,29 @@
+// Copyright 2004-2022 Castle Project - http://www.castleproject.org/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace Castle.DynamicProxy.Tests.Classes
+{
+	using System;
+
+	public partial class Nested
+	{
+#if FEATURE_SERIALIZATION
+			[Serializable]
+#endif
+			[AttributeUsage(AttributeTargets.All, Inherited = false)]
+			public class NonInheritableAttribute : Attribute
+			{
+			}
+	}
+}
diff --git a/src/Castle.Core/DynamicProxy/Internal/AttributeUtil.cs b/src/Castle.Core/DynamicProxy/Internal/AttributeUtil.cs
index e773080c6b..6d41677fa1 100644
--- a/src/Castle.Core/DynamicProxy/Internal/AttributeUtil.cs
+++ b/src/Castle.Core/DynamicProxy/Internal/AttributeUtil.cs
@@ -185,7 +185,7 @@ public static IEnumerable<CustomAttributeInfo> GetNonInheritableAttributes(this
 		/// </summary>
 		private static bool ShouldSkipAttributeReplication(Type attribute, bool ignoreInheritance)
 		{
-			if (attribute.IsPublic == false)
+			if (attribute.IsPublic == false && attribute.IsNestedPublic == false)
 			{
 				return true;
 			}