diff --git a/src/app/FakeLib/MSBuild/ProjectSystem.fs b/src/app/FakeLib/MSBuild/ProjectSystem.fs
index f282bc79a39..8a5c48207ef 100644
--- a/src/app/FakeLib/MSBuild/ProjectSystem.fs
+++ b/src/app/FakeLib/MSBuild/ProjectSystem.fs
@@ -6,19 +6,36 @@ open System.Xml
 open System.Xml.Linq
 
 /// A small abstraction over MSBuild project files.
-type ProjectSystem(projectFileName : string) =
-    let document = 
-        ReadFileAsString projectFileName        
-        |> XMLHelper.XMLDoc
+type ProjectFile(projectFileName:string,documentContent : string) =
+    let document = XMLHelper.XMLDoc documentContent
 
     let nsmgr = 
         let nsmgr = new XmlNamespaceManager(document.NameTable)
         nsmgr.AddNamespace("default", document.DocumentElement.NamespaceURI)
         nsmgr
 
-    let files = 
-        let xpath = "/default:Project/default:ItemGroup/default:Compile/@Include"
-        [for node in document.SelectNodes(xpath,nsmgr) -> node.InnerText]
+    let compileNodesXPath = "/default:Project/default:ItemGroup/default:Compile"
+    let getCompileNodes (document:XmlDocument) =         
+        [for node in document.SelectNodes(compileNodesXPath,nsmgr) -> node]
+
+    let getFileAttributes (document:XmlDocument) = 
+        let xpath = compileNodesXPath + "/@Include"
+        [for attr in document.SelectNodes(xpath,nsmgr) -> attr]
+
+    let files = getFileAttributes document |> List.map (fun attr -> attr.InnerText)
+    
+    /// Read a Project from a FileName
+    static member FromFile(projectFileName) = new ProjectFile(projectFileName,ReadFileAsString projectFileName)
+
+    /// Add a file to the Compile nodes
+    member x.AddFile fileName =        
+        let document = XMLHelper.XMLDoc documentContent // we create a copy and work immutable
+        let node = getCompileNodes document |> Seq.last
+        let newNode = node.CloneNode(false) :?> XmlElement
+        newNode.SetAttribute("Include",fileName)
+        
+        node.ParentNode.AppendChild(newNode) |> ignore
+        new ProjectFile(projectFileName,document.OuterXml)
 
     /// All files which are in "Compile" sections
     member x.Files = files
@@ -40,11 +57,11 @@ type ProjectComparison =
 let findMissingFiles templateProject projects =
     let isFSharpProject file = file |> endsWith ".fsproj"
 
-    let templateFiles = (ProjectSystem templateProject).Files
+    let templateFiles = (ProjectFile.FromFile templateProject).Files
     let templateFilesSet = Set.ofSeq templateFiles
     
     projects
-    |> Seq.map (fun fileName -> ProjectSystem fileName)
+    |> Seq.map (fun fileName -> ProjectFile.FromFile fileName)
     |> Seq.map (fun ps ->             
             let missingFiles = Set.difference templateFilesSet (Set.ofSeq ps.Files)
             let unorderedFiles =
diff --git a/src/test/Test.FAKECore/ProjectSystemSpecs.cs b/src/test/Test.FAKECore/ProjectSystemSpecs.cs
index 2c82d4ccc9e..1b833de1f13 100644
--- a/src/test/Test.FAKECore/ProjectSystemSpecs.cs
+++ b/src/test/Test.FAKECore/ProjectSystemSpecs.cs
@@ -5,8 +5,8 @@ namespace Test.FAKECore
 {
     public class when_checking_for_files
     {
-        static ProjectSystem.ProjectSystem _project;
-        Because of = () => _project = new ProjectSystem.ProjectSystem("ProjectTestFiles/FakeLib.fsproj");
+        static ProjectSystem.ProjectFile _project;
+        Because of = () => _project = ProjectSystem.ProjectFile.FromFile("ProjectTestFiles/FakeLib.fsproj");
 
         It should_find_the_SpecsRemovement_helper_in_the_MSBuild_folder = () =>
             _project.Files.ShouldContain("MSBuild\\SpecsRemovement.fs");
@@ -23,4 +23,17 @@ public class when_checking_for_files
         It should_not_find_the_badadadum_helper = () =>
             _project.Files.ShouldNotContain("badadadumHelper.fs");
     }
+
+    public class when_adding_files
+    {
+        static ProjectSystem.ProjectFile _project;
+        Establish context = () => _project = ProjectSystem.ProjectFile.FromFile("ProjectTestFiles/FakeLib.fsproj");
+        Because of = () => _project = _project.AddFile("badadadumHelper.fs");
+
+        It should_find_the_SpecsRemovement_helper_in_the_MSBuild_folder = () =>
+            _project.Files.ShouldContain("MSBuild\\SpecsRemovement.fs");
+
+        It should_find_the_badadadum_helper = () =>
+            _project.Files.ShouldContain("badadadumHelper.fs");
+    }
 }
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