diff --git a/src/System.Management.Automation/engine/parser/ast.cs b/src/System.Management.Automation/engine/parser/ast.cs
index e99fd1001c..156e0365b4 100644
--- a/src/System.Management.Automation/engine/parser/ast.cs
+++ b/src/System.Management.Automation/engine/parser/ast.cs
@@ -29,11 +29,15 @@ namespace System.Management.Automation.Language
     using System.Runtime.CompilerServices;
     using System.Reflection.Emit;
 
+#nullable enable
+
     internal interface ISupportsAssignment
     {
         IAssignableValue GetAssignableValue();
     }
 
+#nullable restore
+
     internal interface IAssignableValue
     {
         /// <summary>