diff --git a/X10D/src/Collections/EnumerableExtensions.cs b/X10D/src/Collections/EnumerableExtensions.cs
index ddba90e..93e1b67 100644
--- a/X10D/src/Collections/EnumerableExtensions.cs
+++ b/X10D/src/Collections/EnumerableExtensions.cs
@@ -1,4 +1,4 @@
-using System.Diagnostics.Contracts;
+using System.Diagnostics.Contracts;
 
 namespace X10D.Collections;
 
@@ -335,7 +335,7 @@ public static class EnumerableExtensions
     [Pure]
     public static IEnumerable<TSource> WhereNot<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate)
     {
-#if NET6_0
+#if NET6_0_OR_GREATER
         ArgumentNullException.ThrowIfNull(source);
         ArgumentNullException.ThrowIfNull(predicate);
 #else