diff --git a/src/ObservableCollections.Unity/Assets/Plugins/ObservableCollections/Runtime/Shims/Nullables.cs b/src/ObservableCollections.Unity/Assets/Plugins/ObservableCollections/Runtime/Shims/Nullables.cs
index 9b745a3..eba1209 100644
--- a/src/ObservableCollections.Unity/Assets/Plugins/ObservableCollections/Runtime/Shims/Nullables.cs
+++ b/src/ObservableCollections.Unity/Assets/Plugins/ObservableCollections/Runtime/Shims/Nullables.cs
@@ -2,7 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Text;
 
-#if NETSTANDARD2_0 || NET_STANDARD_2_0 || NET_4_6
+#if (NETSTANDARD2_0 || NET_STANDARD_2_0 || NET_4_6) && !UNITY_2021_1_OR_NEWER
 
 namespace System.Diagnostics.CodeAnalysis
 {