diff --git a/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.Build/NugetPackageManager.cs b/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.Build/NugetPackageManager.cs
index dd4f33b..317c23b 100644
--- a/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.Build/NugetPackageManager.cs
+++ b/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.Build/NugetPackageManager.cs
@@ -68,44 +68,45 @@ public bool TryGetUsedPackagesDependendingOnNugetOutput(out ITaskItem[] packages
                 using (var archive = Package.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read))
                 {
                     var nuspec = archive.GetParts().Single(part => part.Uri.ToString().EndsWith(".nuspec"));
-                    var nugetSpec = Path.Combine(nupkgpath, Path.GetFileName(nuspec.Uri.ToString()));
+                    var nuspecFilename = Path.GetFileName(nuspec.Uri.ToString());
+                    var nugetSpec = Path.Combine(nupkgpath, nuspecFilename);
 
                     // use a mutex to ensure that only one process unzip the nuspec
                     // and that one process do not start reading it due to its existence while another one is still writing it.
-                    if (!File.Exists(nugetSpec))
+                    var mut = new Mutex(false, nuspecFilename);
+                    var xml = new XmlDocument();
+                    try
                     {
-                        var mut = new Mutex(false, "UnzipNuSpec");
-                        try
-                        {
-                            mut.WaitOne();
+                        mut.WaitOne();
 
-                            if (!File.Exists(nugetSpec))
-                                try
+                        if (!File.Exists(nugetSpec))
+                        {
+                            try
+                            {
+                                using (
+                                    var outputstream = new FileStream(nugetSpec, FileMode.Create,
+                                        FileAccess.ReadWrite, FileShare.None))
                                 {
-                                    using (
-                                        var outputstream = new FileStream(nugetSpec, FileMode.Create,
-                                            FileAccess.ReadWrite, FileShare.None))
+                                    using (var nspecstream = nuspec.GetStream())
                                     {
-                                        using (var nspecstream = nuspec.GetStream())
-                                        {
-                                            nspecstream.CopyTo(outputstream);
-                                        }
+                                        nspecstream.CopyTo(outputstream);
                                     }
                                 }
-                                catch (IOException)
-                                {
-                                    if (!File.Exists(nugetSpec))
-                                        throw;
-                                }
-                        }
-                        finally
-                        {
-                            mut.ReleaseMutex();
+                            }
+                            catch (IOException)
+                            {
+                                if (!File.Exists(nugetSpec))
+                                    throw;
+                            }
                         }
-                    }
 
-                    var xml = new XmlDocument();
-                    xml.LoadXml(File.ReadAllText(nugetSpec));
+                        xml.Load(nugetSpec);
+                    }
+                    finally
+                    {
+                        mut.ReleaseMutex();
+                    }
+                    
                     var deps = xml.GetElementsByTagName("dependency");
                     foreach (XmlNode dep in deps)
                     {
diff --git a/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.nuspec b/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.nuspec
index b1318df..e6a8eb6 100644
--- a/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.nuspec
+++ b/Baseclass.Contrib.Nuget.Output/Baseclass.Contrib.Nuget.Output.nuspec
@@ -10,8 +10,8 @@
         <projectUrl>http://www.baseclass.ch/Contrib/Nuget</projectUrl>
         <requireLicenseAcceptance>false</requireLicenseAcceptance>
         <description>Treats the "output" folder in an dependend nuget package as an additional special folder and copies it's content to the build folder</description>
-		<releaseNotes xml:space="preserve">- Added support for paket
-- Added support for repository path configuration</releaseNotes>
+		<releaseNotes xml:space="preserve">- Fix concurrency issue regression
+- Reduce scope of the mutex to optimize parallel compilations</releaseNotes>
         <tags>Nuget Targets Copy Output build package convention</tags>
     </metadata>
     <files>