diff --git a/src/Chapter23.Tests/Listing23.20.DesignatingABlockForUnsafeCode.Tests.cs b/src/Chapter23.Tests/Listing23.20.DesignatingABlockForUnsafeCode.Tests.cs
index 6013145d7..af00bca96 100644
--- a/src/Chapter23.Tests/Listing23.20.DesignatingABlockForUnsafeCode.Tests.cs
+++ b/src/Chapter23.Tests/Listing23.20.DesignatingABlockForUnsafeCode.Tests.cs
@@ -2,7 +2,7 @@
 using System.Runtime.InteropServices;
 
 namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter23.Listing23_20.Tests;
-
+#if NET8_0_OR_GREATER
 [TestClass]
 public class Listing21_20_Tests
 {
@@ -21,3 +21,4 @@ public void GetProcessorIdReturnsCorrectValue()
             });
     }
 }
+#endif
\ No newline at end of file
diff --git a/src/Chapter23/Listing23.20.DesignatingABlockForUnsafeCode.cs b/src/Chapter23/Listing23.20.DesignatingABlockForUnsafeCode.cs
index 00ec68959..183254e9f 100644
--- a/src/Chapter23/Listing23.20.DesignatingABlockForUnsafeCode.cs
+++ b/src/Chapter23/Listing23.20.DesignatingABlockForUnsafeCode.cs
@@ -1,5 +1,6 @@
 namespace AddisonWesley.Michaelis.EssentialCSharp.Chapter23.Listing23_20;
 
+#if NET8_0_OR_GREATER
 #region INCLUDE
 using System;
 using System.Runtime.InteropServices;
@@ -268,3 +269,4 @@ public static IntPtr AllocExecutionBlock(int size)
             size, GetCurrentProcessHandle());
     }
 }
+#endif
\ No newline at end of file