diff --git a/src/System.Management.Automation/engine/parser/ast.cs b/src/System.Management.Automation/engine/parser/ast.cs
index 2a126397d5d..05a32506a3c 100644
--- a/src/System.Management.Automation/engine/parser/ast.cs
+++ b/src/System.Management.Automation/engine/parser/ast.cs
@@ -8167,10 +8167,12 @@ public interface ITypeName
         IScriptExtent Extent { get; }
     }
 
+#nullable enable
     internal interface ISupportsTypeCaching
     {
-        Type CachedType { get; set; }
+        Type? CachedType { get; set; }
     }
+#nullable restore
 
     /// <summary>
     /// A simple type that is not an array or does not have generic arguments.