diff --git a/src/NHibernate.Test/MappingByCode/ExplicitMappingTests/ComponentAsIdTests.cs b/src/NHibernate.Test/MappingByCode/ExplicitMappingTests/ComponentAsIdTests.cs
index 2e391577369..d976324c61f 100644
--- a/src/NHibernate.Test/MappingByCode/ExplicitMappingTests/ComponentAsIdTests.cs
+++ b/src/NHibernate.Test/MappingByCode/ExplicitMappingTests/ComponentAsIdTests.cs
@@ -29,6 +29,21 @@ private class MyComponent : IMyCompo
 			public string Name { get; set; }
 		}
 
+		[Test]
+		public void CanSpecifyUnsavedValue()
+		{
+			//NH-3048
+			var mapper = new ModelMapper();
+			mapper.Class<MyClass>(map => map.ComponentAsId(x => x.Id, x =>
+				{
+					x.UnsavedValue(UnsavedValueType.Any);
+				}));
+
+			var mapping = mapper.CompileMappingForAllExplicitlyAddedEntities();
+
+			Assert.AreEqual(mapping.RootClasses[0].CompositeId.unsavedvalue, HbmUnsavedValueType.Any);
+		}
+
 		[Test]
 		public void WhenPropertyUsedAsComposedIdThenRegister()
 		{
diff --git a/src/NHibernate/Mapping/ByCode/ICompositeIdMapper.cs b/src/NHibernate/Mapping/ByCode/ICompositeIdMapper.cs
index 2378f360866..72029634360 100644
--- a/src/NHibernate/Mapping/ByCode/ICompositeIdMapper.cs
+++ b/src/NHibernate/Mapping/ByCode/ICompositeIdMapper.cs
@@ -12,6 +12,8 @@ public interface IComponentAsIdAttributesMapper : IAccessorPropertyMapper
 		/// Useful when the property is an interface and you need the mapping to a concrete class mapped as component.
 		/// </remarks>
 		void Class(System.Type componentType);
+
+		void UnsavedValue(UnsavedValueType unsavedValueType);
 	}
 
 	public interface IComponentAsIdMapper : IComponentAsIdAttributesMapper, IMinimalPlainPropertyContainerMapper { }
@@ -21,6 +23,8 @@ public interface IComposedIdMapper<TEntity> : IMinimalPlainPropertyContainerMapp
 	public interface IComponentAsIdAttributesMapper<TComponent> : IAccessorPropertyMapper
 	{
 		void Class<TConcrete>() where TConcrete : TComponent;
+
+		void UnsavedValue(UnsavedValueType unsavedValueType);
 	}
 
 	public interface IComponentAsIdMapper<TComponent> : IComponentAsIdAttributesMapper<TComponent>, IMinimalPlainPropertyContainerMapper<TComponent>
diff --git a/src/NHibernate/Mapping/ByCode/Impl/ComponentAsIdMapper.cs b/src/NHibernate/Mapping/ByCode/Impl/ComponentAsIdMapper.cs
index 841a1828bda..940112cf879 100644
--- a/src/NHibernate/Mapping/ByCode/Impl/ComponentAsIdMapper.cs
+++ b/src/NHibernate/Mapping/ByCode/Impl/ComponentAsIdMapper.cs
@@ -20,6 +20,11 @@ public ComponentAsIdMapper(System.Type componentType, MemberInfo declaringTypeMe
 			accessorPropertyMapper = new AccessorPropertyMapper(declaringTypeMember.DeclaringType, declaringTypeMember.Name, x => id.access = x);
 		}
 
+		public void UnsavedValue(UnsavedValueType unsavedValueType)
+		{
+			id.unsavedvalue = (HbmUnsavedValueType)Enum.Parse(typeof(HbmUnsavedValueType), unsavedValueType.ToString());
+		}
+
 		public HbmCompositeId CompositeId
 		{
 			get { return id; }
diff --git a/src/NHibernate/Mapping/ByCode/Impl/CustomizersImpl/ComponentAsIdCustomizer.cs b/src/NHibernate/Mapping/ByCode/Impl/CustomizersImpl/ComponentAsIdCustomizer.cs
index 5c398b0f40f..7334a20f281 100644
--- a/src/NHibernate/Mapping/ByCode/Impl/CustomizersImpl/ComponentAsIdCustomizer.cs
+++ b/src/NHibernate/Mapping/ByCode/Impl/CustomizersImpl/ComponentAsIdCustomizer.cs
@@ -19,6 +19,11 @@ public ComponentAsIdCustomizer(IModelExplicitDeclarationsHolder explicitDeclarat
 			explicitDeclarationsHolder.AddAsPoid(propertyPath.LocalMember);
 		}
 
+		public void UnsavedValue(UnsavedValueType unsavedValueType)
+		{
+			CustomizersHolder.AddCustomizer(PropertyPath, (IComponentAsIdAttributesMapper m) => m.UnsavedValue(unsavedValueType));
+		}
+
 		public void Class<TConcrete>() where TConcrete : TComponent
 		{
 			CustomizersHolder.AddCustomizer(PropertyPath, (IComponentAsIdAttributesMapper m) => m.Class(typeof(TConcrete)));
diff --git a/src/NHibernate/Mapping/ByCode/UnsavedValueType.cs b/src/NHibernate/Mapping/ByCode/UnsavedValueType.cs
new file mode 100644
index 00000000000..0109224432b
--- /dev/null
+++ b/src/NHibernate/Mapping/ByCode/UnsavedValueType.cs
@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace NHibernate.Mapping.ByCode
+{
+	public enum UnsavedValueType
+	{
+		Undefined,
+
+		Any,
+
+		None,
+	}
+}
diff --git a/src/NHibernate/NHibernate.csproj b/src/NHibernate/NHibernate.csproj
index 324f64e8cc3..b399d058ce9 100644
--- a/src/NHibernate/NHibernate.csproj
+++ b/src/NHibernate/NHibernate.csproj
@@ -498,6 +498,7 @@
     <Compile Include="Mapping\ByCode\NotFoundMode.cs" />
     <Compile Include="Mapping\ByCode\SchemaAction.cs" />
     <Compile Include="Mapping\ByCode\TypeExtensions.cs" />
+    <Compile Include="Mapping\ByCode\UnsavedValueType.cs" />
     <Compile Include="Mapping\ByCode\VersionGeneration.cs" />
     <Compile Include="Mapping\Collection.cs" />
     <Compile Include="Mapping\Column.cs" />