diff --git a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/BooProject.cs b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/BooProject.cs
index 63b08f3f2c..d3649cbbd3 100644
--- a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/BooProject.cs
+++ b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/BooProject.cs
@@ -102,6 +102,7 @@ namespace Grunwald.BooBinding
 		public override IEnumerable<ReferenceProjectItem> ResolveAssemblyReferences(CancellationToken cancellationToken)
 		{
 			ReferenceProjectItem[] additionalReferences = {
+				new ReferenceProjectItem(this, "mscorlib"),
 				new ReferenceProjectItem(this, "System")
 			};
 			ReferenceProjectItem[] booReferences = {
diff --git a/src/Main/Base/Project/Src/Project/MSBuildBasedProject.cs b/src/Main/Base/Project/Src/Project/MSBuildBasedProject.cs
index 74ab7c382a..aebdc6962a 100644
--- a/src/Main/Base/Project/Src/Project/MSBuildBasedProject.cs
+++ b/src/Main/Base/Project/Src/Project/MSBuildBasedProject.cs
@@ -145,7 +145,10 @@ namespace ICSharpCode.SharpDevelop.Project
 		
 		public override IEnumerable<ReferenceProjectItem> ResolveAssemblyReferences(CancellationToken cancellationToken)
 		{
-			return MSBuildInternals.ResolveAssemblyReferences(this);
+			ReferenceProjectItem[] additionalItems = {
+				new ReferenceProjectItem(this, "mscorlib")
+			};
+			return MSBuildInternals.ResolveAssemblyReferences(this, additionalItems);
 		}
 		
 		#region CreateProjectItem
@@ -177,7 +180,7 @@ namespace ICSharpCode.SharpDevelop.Project
 					
 				case "WebReferences":
 					return new WebReferencesProjectItem(this, item);
-				
+					
 				case "WCFMetadata":
 					return new ServiceReferencesProjectItem(this, item);