diff --git a/X10D.Tests/src/Collections/Int16Tests.cs b/X10D.Tests/src/Collections/Int16Tests.cs
index 9e44f49..8672a0a 100644
--- a/X10D.Tests/src/Collections/Int16Tests.cs
+++ b/X10D.Tests/src/Collections/Int16Tests.cs
@@ -1,4 +1,6 @@
-using System.Runtime.Intrinsics.X86;
+#if NET5_0_OR_GREATER
+using System.Runtime.Intrinsics.X86;
+#endif
 using NUnit.Framework;
 using X10D.Collections;
 
diff --git a/X10D.Tests/src/Collections/Int32Tests.cs b/X10D.Tests/src/Collections/Int32Tests.cs
index 219ecd3..97485e1 100644
--- a/X10D.Tests/src/Collections/Int32Tests.cs
+++ b/X10D.Tests/src/Collections/Int32Tests.cs
@@ -1,4 +1,6 @@
-using System.Runtime.Intrinsics.X86;
+#if NET5_0_OR_GREATER
+using System.Runtime.Intrinsics.X86;
+#endif
 using NUnit.Framework;
 using X10D.Collections;