diff --git a/XmlSchemaClassGenerator/Substitute.cs b/XmlSchemaClassGenerator/Substitute.cs
index 1243046e..e9c03e00 100644
--- a/XmlSchemaClassGenerator/Substitute.cs
+++ b/XmlSchemaClassGenerator/Substitute.cs
@@ -5,7 +5,7 @@
 
 namespace XmlSchemaClassGenerator
 {
-    public class Substitute: IEquatable<Substitute>
+    public sealed class Substitute: IEquatable<Substitute>
     {
         public XmlSchemaElement Element { get; set; }
         public TypeModel Type { get; set; }
diff --git a/appveyor.yml b/appveyor.yml
index 29daaf32..02c3786c 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -6,6 +6,7 @@ environment:
     secure: Eq6BjtZ80BXKLwFMg76IjuQAvbLjbojIF/X/ARouGVhxPneJtgDfCXMPNgJ7KBKq
   sonar_token:
     secure: W7pHKhuTW6Lh8WlXJNTOIaOzeuxLi+H6Nqmnm4pr28jM6jyIpOZ+1r10lIQi0eCA
+  JAVA_HOME: C:\Program Files\Java\jdk14
 nuget:
   disable_publish_on_pr: true
 build_script: