diff --git a/ILRuntime/Runtime/Stack/StackObject.cs b/ILRuntime/Runtime/Stack/StackObject.cs
index 579616be..7438ca9c 100644
--- a/ILRuntime/Runtime/Stack/StackObject.cs
+++ b/ILRuntime/Runtime/Stack/StackObject.cs
@@ -223,7 +223,8 @@ public unsafe static void Initialized(StackObject* esp, IType type)
             }
             else if (type.IsEnum)
             {
-                if(type is ILType ilType)
+                ILType ilType = type as ILType;
+                if (ilType != null)
                 {
                     Initialized(esp, ilType.FieldTypes[0]);
                 }