diff --git a/EnvelopeGenerator.Domain/Entities/Envelope.cs b/EnvelopeGenerator.Domain/Entities/Envelope.cs
index b3f1ffa8..8d23e81d 100644
--- a/EnvelopeGenerator.Domain/Entities/Envelope.cs
+++ b/EnvelopeGenerator.Domain/Entities/Envelope.cs
@@ -126,7 +126,11 @@ public class Envelope
     public User User { get; set; }
 
     [ForeignKey("EnvelopeTypeId")]
-    public EnvelopeType EnvelopeType { get; set; }
+    public virtual EnvelopeType
+#if NET
+        ?
+#endif
+        EnvelopeType { get; set; }
 
 #if NETFRAMEWORK
     [NotMapped]