diff --git a/ICSharpCode.NRefactory.CSharp/CSharpProjectContent.cs b/ICSharpCode.NRefactory.CSharp/CSharpProjectContent.cs
index bdc2040490..e3429861c2 100644
--- a/ICSharpCode.NRefactory.CSharp/CSharpProjectContent.cs
+++ b/ICSharpCode.NRefactory.CSharp/CSharpProjectContent.cs
@@ -87,7 +87,7 @@ namespace ICSharpCode.NRefactory.CSharp
 				return null;
 		}
 		
-		public ICompilation CreateCompilation()
+		public virtual ICompilation CreateCompilation()
 		{
 			var solutionSnapshot = new DefaultSolutionSnapshot();
 			ICompilation compilation = new SimpleCompilation(solutionSnapshot, this, assemblyReferences);
@@ -95,28 +95,33 @@ namespace ICSharpCode.NRefactory.CSharp
 			return compilation;
 		}
 		
-		public ICompilation CreateCompilation(ISolutionSnapshot solutionSnapshot)
+		public virtual ICompilation CreateCompilation(ISolutionSnapshot solutionSnapshot)
 		{
 			return new SimpleCompilation(solutionSnapshot, this, assemblyReferences);
 		}
 		
+		protected virtual CSharpProjectContent Clone()
+		{
+			return new CSharpProjectContent(this);
+		}
+		
 		public IProjectContent SetAssemblyName(string newAssemblyName)
 		{
-			CSharpProjectContent pc = new CSharpProjectContent(this);
+			CSharpProjectContent pc = Clone();
 			pc.assemblyName = newAssemblyName;
 			return pc;
 		}
 		
 		public IProjectContent AddAssemblyReferences(IEnumerable<IAssemblyReference> references)
 		{
-			CSharpProjectContent pc = new CSharpProjectContent(this);
+			CSharpProjectContent pc = Clone();
 			pc.assemblyReferences.AddRange(references);
 			return pc;
 		}
 		
 		public IProjectContent RemoveAssemblyReferences(IEnumerable<IAssemblyReference> references)
 		{
-			CSharpProjectContent pc = new CSharpProjectContent(this);
+			CSharpProjectContent pc = Clone();
 			pc.assemblyReferences.RemoveAll(r => references.Contains(r));
 			return pc;
 		}
@@ -129,7 +134,7 @@ namespace ICSharpCode.NRefactory.CSharp
 				if (!Platform.FileNameComparer.Equals(oldFile.FileName, newFile.FileName))
 					throw new ArgumentException("When both oldFile and newFile are specified, they must use the same file name.");
 			}
-			CSharpProjectContent pc = new CSharpProjectContent(this);
+			CSharpProjectContent pc = Clone();
 			if (newFile == null)
 				pc.parsedFiles.Remove(oldFile.FileName);
 			else
@@ -139,7 +144,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public IProjectContent UpdateProjectContent(IEnumerable<IParsedFile> oldFiles, IEnumerable<IParsedFile> newFiles)
 		{
-			CSharpProjectContent pc = new CSharpProjectContent(this);
+			CSharpProjectContent pc = Clone();
 			if (oldFiles != null) {
 				foreach (var oldFile in oldFiles) {
 					pc.parsedFiles.Remove(oldFile.FileName);