diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/CheckForDuplicateItems.cs b/src/Tasks/Microsoft.NET.Build.Tasks/CheckForDuplicateItems.cs
index e7e09bae2bcc..adff515f0a02 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/CheckForDuplicateItems.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/CheckForDuplicateItems.cs
@@ -35,7 +35,7 @@ protected override void ExecuteCore()
 
             if (DefaultItemsEnabled && DefaultItemsOfThisTypeEnabled)
             {
-                var itemGroups = Items.GroupBy(i => i.ItemSpec, StringComparer.OrdinalIgnoreCare);
+                var itemGroups = Items.GroupBy(i => i.ItemSpec, StringComparer.OrdinalIgnoreCase);
 
                 var duplicateItems = itemGroups.Where(g => g.Count() > 1).ToList();
                 if (duplicateItems.Any())