2 files changed, 6 insertions, 6 deletions
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/node/ConstantNode.java b/chapter11/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
index cf1a76b0..31edb848 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
@@ -18,7 +18,7 @@ import java.util.BitSet;
  * The Constant's value is the value stored in it.
  */
 public class ConstantNode extends Node {
-    Type _con;
+    final Type _con;
     public ConstantNode( Type type ) {
         super(Parser.START);
         _con = type;
diff --git a/chapter11/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java b/chapter11/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
index 65352402..9392da20 100644
--- a/chapter11/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
+++ b/chapter11/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
@@ -29,11 +29,11 @@ public class TypeMemPtr extends Type {
     public static TypeMemPtr make(TypeStruct obj, boolean nil) { return new TypeMemPtr(obj, nil).intern(); }
     public static TypeMemPtr make(TypeStruct obj) { return TypeMemPtr.make(obj, false); }
 
-    public static TypeMemPtr BOT = make(TypeStruct.BOT,true);
-    public static TypeMemPtr TOP = BOT.dual();
-    public static TypeMemPtr NULLPTR = make(TypeStruct.TOP,true);
-    public static TypeMemPtr VOIDPTR = NULLPTR.dual(); // A bottom mix of not-null ptrs, like C's void* but not null
-    public static TypeMemPtr TEST= make(TypeStruct.TEST,false);
+    public static final TypeMemPtr BOT = make(TypeStruct.BOT,true);
+    public static final TypeMemPtr TOP = BOT.dual();
+    public static final TypeMemPtr NULLPTR = make(TypeStruct.TOP,true);
+    public static final TypeMemPtr VOIDPTR = NULLPTR.dual(); // A bottom mix of not-null ptrs, like C's void* but not null
+    public static final TypeMemPtr TEST= make(TypeStruct.TEST,false);
     public static void gather(ArrayList<Type> ts) { ts.add(NULLPTR); ts.add(BOT); ts.add(TEST); }
 
     @Override