diff --git a/mutants/mutant-4/swen90006/machine/Machine.java b/mutants/mutant-4/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..b579436123478d4cabbb86b7282f5d5b120a1495 100644
--- a/mutants/mutant-4/swen90006/machine/Machine.java
+++ b/mutants/mutant-4/swen90006/machine/Machine.java
@@ -63,7 +63,7 @@ public class Machine
     
   private void do_sub(int dest, int src1, int src2)
   {
-    regs[dest] = regs[src1] - regs[src2];
+    regs[dest] = regs[src2] - regs[src1];
   }
     
   private void do_mult(int dest, int src1, int src2)