diff -r 960e219425e2 -r 189f695d0b02 vm/src/test/java/org/apidesign/vm4brwsr/Numbers.java
--- a/vm/src/test/java/org/apidesign/vm4brwsr/Numbers.java	Thu Jan 31 13:55:12 2013 +0100
+++ b/vm/src/test/java/org/apidesign/vm4brwsr/Numbers.java	Thu Jan 31 15:26:09 2013 +0100
@@ -80,8 +80,12 @@
         return (disX.readLong() + disY.readLong());
     }
     
-    public static long subL(long x, long y) {
-        return (x - y);
+    public static long subL(byte[] arrX, byte[] arrY) throws IOException {
+        ByteArrayInputStream isX = new ByteArrayInputStream(arrX);
+        DataInputStream disX = new DataInputStream(isX);
+        ByteArrayInputStream isY = new ByteArrayInputStream(arrY);
+        DataInputStream disY = new DataInputStream(isY);
+        return (disX.readLong() - disY.readLong());
     }
     
     public static long mulL(long x, long y) {