diff --git a/vm.go b/vm.go
index 353f4f39e..dc026f318 100644
--- a/vm.go
+++ b/vm.go
@@ -60,8 +60,6 @@ type TxCallback func(opType OpType) bool
 type Vm struct {
   // Memory stack
   stack map[string]string
-  // Index ptr
-  iptr int
   memory map[string]map[string]string
 }
 
@@ -71,7 +69,10 @@ func NewVm() *Vm {
   stackSize := uint(256)
   fmt.Println("stack size =", stackSize)
 
-  return &Vm{make(map[string]string), 0, make(map[string]map[string]string)}
+  return &Vm{
+    stack: make(map[string]string),
+    memory: make(map[string]map[string]string),
+  }
 }
 
 func (vm *Vm) RunTransaction(tx *Transaction, cb TxCallback) {
@@ -84,6 +85,8 @@ func (vm *Vm) RunTransaction(tx *Transaction, cb TxCallback) {
   vm.stack["0"] = tx.sender
   vm.stack["1"] = "100"  //int(tx.value)
   vm.stack["1"] = "1000" //int(tx.fee)
+  // Stack pointer
+  stPtr := 0
 
   //vm.memory[tx.addr] = make([]int, 256)
   vm.memory[tx.addr] = make(map[string]string)
@@ -93,13 +96,13 @@ func (vm *Vm) RunTransaction(tx *Transaction, cb TxCallback) {
   // Instructions are shorthanded as Ix/y/z
   x := 0; y := 1; z := 2; //a := 3; b := 4; c := 5
 out:
-  for vm.iptr < len(tx.data) {
+  for stPtr < len(tx.data) {
     // The base big int for all calculations. Use this for any results.
     base := new(big.Int)
     // XXX Should Instr return big int slice instead of string slice?
-    op, args, _ := Instr(tx.data[vm.iptr])
+    op, args, _ := Instr(tx.data[stPtr])
 
-    fmt.Printf("%-3d %d %v\n", vm.iptr, op, args)
+    fmt.Printf("%-3d %d %v\n", stPtr, op, args)
 
     opType     := OpType(tNorm)
     // Determine the op type (used for calculating fees by the block manager)
@@ -113,7 +116,7 @@ out:
     // If the callback yielded a negative result abort execution
     if !cb(opType) { break out }
 
-    nptr := vm.iptr
+    nptr := stPtr
     switch op {
     case oSTOP:
       fmt.Println("exiting (oSTOP), idx =", nptr)
@@ -171,10 +174,10 @@ out:
       break
     }
 
-    if vm.iptr == nptr {
-      vm.iptr++
+    if stPtr == nptr {
+      stPtr++
     } else {
-      vm.iptr = nptr
+      stPtr = nptr
       fmt.Println("... JMP", nptr, "...")
     }
   }