diff --git a/mutants/mutant-4/swen90006/machine/Machine.java b/mutants/mutant-4/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..22abf16b6c7f28553e8acbebc62e73d441dcf68f 100644
--- a/mutants/mutant-4/swen90006/machine/Machine.java
+++ b/mutants/mutant-4/swen90006/machine/Machine.java
@@ -140,7 +140,7 @@ public class Machine
   private void validate_reg(int reg)
     throws InvalidInstructionException
   {
-    if (reg < 0 || reg > MAX_REG) {
+    if (reg < 0 && reg > MAX_REG) {
       throw new InvalidInstructionException();
     }
   }
@@ -170,7 +170,7 @@ public class Machine
     int pc = 0;
     final int progLength = instructions.size();
     while(true){
-      if (pc < 0 || pc >= progLength){
+      if (pc < 0 && pc >= progLength){
 	/* will cause NoReturnValueException to be thrown
 	 * but that is not a bug and and indeed is what the
 	 * VM is supposed to do if the pc becomes negative,