diff --git a/src/Workspaces/Core/Portable/Options/SerializableOptionSet.cs b/src/Workspaces/Core/Portable/Options/SerializableOptionSet.cs
index 53ea1b5961243a94f99be506c9e8641b79eaf85c..a53c7f486f74c9909a876fa62dc12e3316563546 100644
--- a/src/Workspaces/Core/Portable/Options/SerializableOptionSet.cs
+++ b/src/Workspaces/Core/Portable/Options/SerializableOptionSet.cs
@@ -254,7 +254,8 @@ public void Serialize(ObjectWriter writer, CancellationToken cancellationToken)
                 }
                 else if (kind == OptionValueKind.CodeStyleOption || kind == OptionValueKind.NamingStylePreferences)
                 {
-                    ((IObjectWritable)value!).WriteTo(writer);
+                    RoslynDebug.Assert(value != null);
+                    ((IObjectWritable)value).WriteTo(writer);
                 }
                 else
                 {