diff --git a/mutants/mutant-2/swen90006/machine/Machine.java b/mutants/mutant-2/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..0939a8c8fbfd5e564f09dd5a5cc585b84b5d19bc 100644
--- a/mutants/mutant-2/swen90006/machine/Machine.java
+++ b/mutants/mutant-2/swen90006/machine/Machine.java
@@ -211,7 +211,7 @@ public class Machine
 	int rs2 = parseReg(toks[3]);
 	do_add(rd,rs1,rs2);
       } else if (toks[0].equals(INSTRUCTION_SUBTRACT)){
-	if (toks.length != 4){
+	if (toks.length = 4){
 	  throw new InvalidInstructionException();
 	}
 	int rd = parseReg(toks[1]);
diff --git a/mutants/mutant-3/swen90006/machine/Machine.java b/mutants/mutant-3/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..ea9d43b06cc9f16d05e1af3338dc3f815f1d2511 100644
--- a/mutants/mutant-3/swen90006/machine/Machine.java
+++ b/mutants/mutant-3/swen90006/machine/Machine.java
@@ -91,9 +91,9 @@ public class Machine
   }
 
   private void do_store(int a, int offs, int b)  {
-    if (regs[a] + offs > MAX_ADDR){
+    if (regs[a] + offs < MAX_ADDR){
       /* no op */
-    }else if(regs[a] + offs < 0){
+    }else if(regs[a] + offs > 0){
       /* no op */
     }else{
       memory[regs[a] + offs] = regs[b];
diff --git a/mutants/mutant-4/swen90006/machine/Machine.java b/mutants/mutant-4/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..f3d8622cca181d580d3c3e7adf90010b312db690 100644
--- a/mutants/mutant-4/swen90006/machine/Machine.java
+++ b/mutants/mutant-4/swen90006/machine/Machine.java
@@ -58,7 +58,7 @@ public class Machine
 
   private void do_add(int dest, int src1, int src2)
   {
-    regs[dest] = regs[src1] + regs[src2];
+    regs[dest] = regs[src1] = regs[src2];
   }
     
   private void do_sub(int dest, int src1, int src2)
diff --git a/mutants/mutant-5/swen90006/machine/Machine.java b/mutants/mutant-5/swen90006/machine/Machine.java
index 9bf57316d1c736ea2bd1c62bd6df3c6c0282f331..e0c1ba79d8a5e87f3339003160d5d69f35565d30 100644
--- a/mutants/mutant-5/swen90006/machine/Machine.java
+++ b/mutants/mutant-5/swen90006/machine/Machine.java
@@ -266,7 +266,7 @@ public class Machine
 	  throw new InvalidInstructionException();
 	}
 	int offs = parseOffset(toks[1]);
-	pc  = pc + offs;
+	pc  = pc = offs;
 	count++;
 	continue; /* avoid default increment of pc below */
       } else if (toks[0].equals(INSTRUCTION_JZ)){