diff --git a/mutants/mutant-1/swen90006/machine/Machine.java b/mutants/mutant-1/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..070ebfedbc782ad4b358dad03f47e1b0fcf2ec57 100644
--- a/mutants/mutant-1/swen90006/machine/Machine.java
+++ b/mutants/mutant-1/swen90006/machine/Machine.java
@@ -266,7 +266,10 @@ public class Machine
 	  throw new InvalidInstructionException();
 	}
 	int offs = parseOffset(toks[1]);
-	pc  = pc + offs;
+if (offs!=0) {
+     pc  = pc + offs;
+          }
+          else throw new InvalidInstructionException();
 	count++;
 	continue; /* avoid default increment of pc below */
       } else if (toks[0].equals(INSTRUCTION_JZ)){