diff --git a/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/InsertCtorDialog.xaml.cs b/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/InsertCtorDialog.xaml.cs
index 93d416acaf..fd6442122a 100644
--- a/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/InsertCtorDialog.xaml.cs
+++ b/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/InsertCtorDialog.xaml.cs
@@ -40,17 +40,20 @@ namespace SharpRefactoring.Gui
 		
 		protected override string GenerateCode(LanguageProperties language, IClass currentClass)
 		{
-			var line = editor.Document.GetLineForOffset(anchor.Offset);
+			IDocumentLine line = editor.Document.GetLineForOffset(anchor.Offset);
 			
 			string indent = DocumentUtilitites.GetWhitespaceAfter(editor.Document, line.Offset);
 			
-			var filtered = parameterList.Where(p => p.IsSelected).OrderBy(p => p.Index).ToList();
+			List<PropertyOrFieldWrapper> filtered = parameterList
+				.Where(p => p.IsSelected)
+				.OrderBy(p => p.Index)
+				.ToList();
 			
 			BlockStatement block = new BlockStatement();
 			
 			foreach (PropertyOrFieldWrapper w in filtered) {
 				if (w.AddCheckForNull) {
-					if (w.Type.IsReferenceType == true)
+					if (w.Type.IsReferenceType == true || PropertyOrFieldWrapper.IsGenericReferenceType(w.Type))
 						block.AddChild(
 							new IfElseStatement(
 								new BinaryOperatorExpression(new IdentifierExpression(w.ParameterName), BinaryOperatorType.Equality, new PrimitiveExpression(null)),
diff --git a/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/PropertyOrFieldWrapper.cs b/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/PropertyOrFieldWrapper.cs
index 8e2cdfa228..a9d0f23b05 100644
--- a/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/PropertyOrFieldWrapper.cs
+++ b/src/AddIns/Misc/SharpRefactoring/Project/Src/Gui/PropertyOrFieldWrapper.cs
@@ -58,11 +58,21 @@ namespace SharpRefactoring.Gui
 		
 		public bool IsNullable {
 			get {
-				return member.ReturnType.IsReferenceType == true ||
-					member.ReturnType.IsConstructedReturnType && member.ReturnType.Name == "Nullable";
+				return member.ReturnType.IsReferenceType == true
+					|| member.ReturnType.IsConstructedReturnType && member.ReturnType.Name == "Nullable"
+					|| IsGenericReferenceType(member.ReturnType);
 			}
 		}
 		
+		public static bool IsGenericReferenceType(IReturnType type)
+		{
+			if (type == null || !type.IsGenericReturnType)
+				return false;
+			ITypeParameter param = type.CastToGenericReturnType().TypeParameter;
+			return param.HasReferenceTypeConstraint
+				|| param.Constraints.Any(constr => constr.IsReferenceType == true);
+		}
+		
 		public bool HasRange {
 			get {
 				return IsTypeWithRange(member.ReturnType) ||