diff --git a/src/Workspaces/Core/Portable/Options/OptionSet.cs b/src/Workspaces/Core/Portable/Options/OptionSet.cs
index bcafaea49ad2c..d2e481a90e16a 100644
--- a/src/Workspaces/Core/Portable/Options/OptionSet.cs
+++ b/src/Workspaces/Core/Portable/Options/OptionSet.cs
@@ -22,7 +22,7 @@ public abstract partial class OptionSet
 
         private readonly Func<OptionKey, object?> _getOptionCore;
 
-        public OptionSet()
+        protected OptionSet()
         {
             _getOptionCore = GetOptionCore;
         }