--- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/AlwaysValidAssumption.java	Sat Dec 14 02:57:09 2013 +0100
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/AlwaysValidAssumption.java	Sat Dec 14 03:04:01 2013 +0100
@@ -31,17 +31,20 @@
  * An assumption that is always valid. Used as a placeholder where an assumption is needed but never
  * invalidated.
  */
-public class AlwaysValidAssumption implements Assumption {
+public final class AlwaysValidAssumption implements Assumption {
 
     public static final AlwaysValidAssumption INSTANCE = new AlwaysValidAssumption();
 
+    private AlwaysValidAssumption() {
+    }
+
     @Override
     public void check() throws InvalidAssumptionException {
     }
 
     @Override
     public void invalidate() {
-        throw new UnsupportedOperationException("Cannot invalidation this assumption - it is always valid");
+        throw new UnsupportedOperationException("Cannot invalidate this assumption - it is always valid");
     }
 
     @Override