diff --git a/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeElement.cs b/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeElement.cs
index 8de4c1504b..3dc6924b64 100644
--- a/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeElement.cs
+++ b/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeElement.cs
@@ -7,7 +7,7 @@ using ICSharpCode.SharpDevelop.Project;
 
 namespace ICSharpCode.PackageManagement.EnvDTE
 {
-	public class CodeElement : MarshalByRefObject, global::EnvDTE.CodeElement
+	public class CodeElement : global::EnvDTE.CodeElementBase, global::EnvDTE.CodeElement
 	{
 		DTE dte;
 		
@@ -68,5 +68,10 @@ namespace ICSharpCode.PackageManagement.EnvDTE
 		public virtual global::EnvDTE.vsCMElement Kind {
 			get { return global::EnvDTE.vsCMElement.vsCMElementOther; }
 		}
+		
+		protected override bool GetIsDerivedFrom(string fullName)
+		{
+			return false;
+		}
 	}
 }
diff --git a/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeType.cs b/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeType.cs
index d7433c1690..471ce3d0be 100644
--- a/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeType.cs
+++ b/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/CodeType.cs
@@ -83,7 +83,7 @@ namespace ICSharpCode.PackageManagement.EnvDTE
 		/// Returns true if the current type matches the fully qualified name or any of its
 		/// base types are a match.
 		/// </summary>
-		public virtual bool IsDerivedFrom(string fullName)
+		protected override bool GetIsDerivedFrom(string fullName)
 		{
 			return Class.IsDerivedFrom(fullName);
 		}
diff --git a/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/ProjectItem.cs b/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/ProjectItem.cs
index 6b5615fa85..3e1d42c0b1 100644
--- a/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/ProjectItem.cs
+++ b/src/AddIns/Misc/PackageManagement/Project/Src/EnvDTE/ProjectItem.cs
@@ -13,7 +13,7 @@ using SD = ICSharpCode.SharpDevelop.Project;
 
 namespace ICSharpCode.PackageManagement.EnvDTE
 {
-	public class ProjectItem : MarshalByRefObject, global::EnvDTE.ProjectItem
+	public class ProjectItem : global::EnvDTE.ProjectItemBase, global::EnvDTE.ProjectItem
 	{
 		SD.FileProjectItem projectItem;
 		Project containingProject;
@@ -177,7 +177,7 @@ namespace ICSharpCode.PackageManagement.EnvDTE
 			get { return projectItem; }
 		}
 		
-		public virtual string FileNames(short index)
+		protected override string GetFileNames(short index)
 		{
 			return FileName;
 		}
diff --git a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/SharpDevelop.EnvDTE.vbproj b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/SharpDevelop.EnvDTE.vbproj
index 0661024977..e002abf0b0 100644
--- a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/SharpDevelop.EnvDTE.vbproj
+++ b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/SharpDevelop.EnvDTE.vbproj
@@ -90,6 +90,7 @@
     <Compile Include="Src\ItemOperations.vb" />
     <Compile Include="Src\Project.vb" />
     <Compile Include="Src\ProjectItem.vb" />
+    <Compile Include="Src\ProjectItemBase.vb" />
     <Compile Include="Src\ProjectItems.vb" />
     <Compile Include="Src\ProjectObject.vb" />
     <Compile Include="Src\Projects.vb" />
@@ -128,5 +129,8 @@
   <ItemGroup>
     <Compile Include="Src\Constants.vb" />
   </ItemGroup>
+  <ItemGroup>
+    <Compile Include="Src\CodeElementBase.vb" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.VisualBasic.targets" />
 </Project>
\ No newline at end of file
diff --git a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeElementBase.vb b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeElementBase.vb
new file mode 100644
index 0000000000..9aa975c7e5
--- /dev/null
+++ b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeElementBase.vb
@@ -0,0 +1,16 @@
+' Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+' This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+Namespace EnvDTE
+	Public MustInherit Class CodeElementBase
+		Inherits MarshalByRefObject
+		
+		ReadOnly Property IsDerivedFrom(fullName As String) As Boolean
+			Get
+				Return GetIsDerivedFrom(fullName)
+			End Get
+		End Property
+		
+		Protected MustOverride Function GetIsDerivedFrom(ByVal fullName As String) As Boolean
+	End Class
+End Namespace
\ No newline at end of file
diff --git a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeType.vb b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeType.vb
index 39480aa503..2c178b00a0 100644
--- a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeType.vb
+++ b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/CodeType.vb
@@ -17,6 +17,6 @@ Namespace EnvDTE
 		''' Returns true if the current type matches the fully qualified name or any of its
 		''' base types are a match.
 		''' </summary>
-		Function IsDerivedFrom(fullName As String) As Boolean
+		ReadOnly Property IsDerivedFrom (fullName As String) As Boolean
 	End Interface
 End Namespace
\ No newline at end of file
diff --git a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItem.vb b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItem.vb
index 7b6445075f..b8dfe7577c 100644
--- a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItem.vb
+++ b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItem.vb
@@ -11,11 +11,11 @@ Namespace EnvDTE
 		ReadOnly Property ProjectItems() As ProjectItems
 		ReadOnly Property FileCodeModel() As FileCodeModel2
 		ReadOnly Property Document() As Document
+		ReadOnly Property FileNames(index As Short) As String
 		ReadOnly Property FileCount() As Short
 		
 		Sub Delete()
 		Sub Remove()
-		Function FileNames(index As Short) As String
 		Function Open(viewKind As String) As Global.EnvDTE.Window
 	End Interface
 End Namespace
\ No newline at end of file
diff --git a/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItemBase.vb b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItemBase.vb
new file mode 100644
index 0000000000..d241db32ee
--- /dev/null
+++ b/src/AddIns/Misc/PackageManagement/SharpDevelop.EnvDTE/Src/ProjectItemBase.vb
@@ -0,0 +1,16 @@
+' Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+' This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+Namespace EnvDTE
+	Public MustInherit Class ProjectItemBase
+		Inherits MarshalByRefObject
+		
+		ReadOnly Property FileNames(index As Short) As String
+			Get
+				Return GetFileNames(index)
+			End Get
+		End Property
+		
+		Protected MustOverride Function GetFileNames(ByVal index As Short) As String
+	End Class
+End Namespace
\ No newline at end of file
diff --git a/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/CodeTypeTests.cs b/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/CodeTypeTests.cs
index 327b1a3a83..9359776cab 100644
--- a/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/CodeTypeTests.cs
+++ b/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/CodeTypeTests.cs
@@ -137,7 +137,7 @@ namespace PackageManagement.Tests.EnvDTE
 			CreateClass("System.Web.Mvc.ActionResult");
 			CreateCodeType();
 			
-			bool derivedFrom = codeType.IsDerivedFrom("System.Web.Mvc.ActionResult");
+			bool derivedFrom = codeType.get_IsDerivedFrom("System.Web.Mvc.ActionResult");
 			
 			Assert.IsTrue(derivedFrom);
 		}
@@ -150,7 +150,7 @@ namespace PackageManagement.Tests.EnvDTE
 			AddClassInheritanceTree("System.Object");
 			CreateCodeType();
 			
-			bool derivedFrom = codeType.IsDerivedFrom("System.Web.Mvc.ActionResult");
+			bool derivedFrom = codeType.get_IsDerivedFrom("System.Web.Mvc.ActionResult");
 			
 			Assert.IsFalse(derivedFrom);
 		}
@@ -163,7 +163,7 @@ namespace PackageManagement.Tests.EnvDTE
 			helper.AddBaseTypeToClass("System.Web.Mvc.ActionResult");
 			CreateCodeType();
 			
-			bool derivedFrom = codeType.IsDerivedFrom("System.Web.Mvc.ActionResult");
+			bool derivedFrom = codeType.get_IsDerivedFrom("System.Web.Mvc.ActionResult");
 			
 			Assert.IsTrue(derivedFrom);
 		}
@@ -176,7 +176,7 @@ namespace PackageManagement.Tests.EnvDTE
 			AddClassInheritanceTree("CustomActionResultBase", "System.Web.Mvc.ActionResult");
 			CreateCodeType();
 			
-			bool derivedFrom = codeType.IsDerivedFrom("System.Web.Mvc.ActionResult");
+			bool derivedFrom = codeType.get_IsDerivedFrom("System.Web.Mvc.ActionResult");
 			
 			Assert.IsTrue(derivedFrom);
 		}
@@ -190,7 +190,7 @@ namespace PackageManagement.Tests.EnvDTE
 			AddClassInheritanceTree("CustomActionResultBase", "System.Web.Mvc.ActionResult");
 			CreateCodeType();
 			
-			bool derivedFrom = codeType.IsDerivedFrom("System.Web.Mvc.ActionResult");
+			bool derivedFrom = codeType.get_IsDerivedFrom("System.Web.Mvc.ActionResult");
 			
 			Assert.IsTrue(derivedFrom);
 		}
diff --git a/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/ProjectItemTests.cs b/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/ProjectItemTests.cs
index 8d37d95bfc..2802f6643d 100644
--- a/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/ProjectItemTests.cs
+++ b/src/AddIns/Misc/PackageManagement/Test/Src/EnvDTE/ProjectItemTests.cs
@@ -245,7 +245,7 @@ namespace PackageManagement.Tests.EnvDTE
 			msbuildProject.AddFile(@"src\program.cs");
 			global::EnvDTE.ProjectItem directoryItem = projectItems.Item("src");
 			
-			string fileName = directoryItem.FileNames(1);
+			string fileName = directoryItem.get_FileNames(1);
 			
 			Assert.AreEqual(@"d:\projects\MyProject\src", fileName);
 		}