diff --git a/ethchain/closure.go b/ethchain/closure.go
index f8e692f61..2e809aa9d 100644
--- a/ethchain/closure.go
+++ b/ethchain/closure.go
@@ -15,7 +15,8 @@ type Callee interface {
 type ClosureBody interface {
 	Callee
 	ethutil.RlpEncodable
-	GetMem(int64) *ethutil.Value
+	GetMem(*big.Int) *ethutil.Value
+	SetMem(*big.Int, *ethutil.Value)
 }
 
 // Basic inline closure object which implement the 'closure' interface
@@ -36,7 +37,7 @@ func NewClosure(callee Callee, object ClosureBody, state *State, gas, val *big.I
 }
 
 // Retuns the x element in data slice
-func (c *Closure) GetMem(x int64) *ethutil.Value {
+func (c *Closure) GetMem(x *big.Int) *ethutil.Value {
 	m := c.object.GetMem(x)
 	if m == nil {
 		return ethutil.EmptyValue()
@@ -45,6 +46,10 @@ func (c *Closure) GetMem(x int64) *ethutil.Value {
 	return m
 }
 
+func (c *Closure) SetMem(x *big.Int, val *ethutil.Value) {
+	c.object.SetMem(x, val)
+}
+
 func (c *Closure) Address() []byte {
 	return c.object.Address()
 }
diff --git a/ethchain/contract.go b/ethchain/contract.go
index 93d2b68ba..f7ae01753 100644
--- a/ethchain/contract.go
+++ b/ethchain/contract.go
@@ -39,12 +39,17 @@ func (c *Contract) State() *State {
 	return c.state
 }
 
-func (c *Contract) GetMem(num int64) *ethutil.Value {
-	nb := ethutil.BigToBytes(big.NewInt(num), 256)
+func (c *Contract) GetMem(num *big.Int) *ethutil.Value {
+	nb := ethutil.BigToBytes(num, 256)
 
 	return c.Addr(nb)
 }
 
+func (c *Contract) SetMem(num *big.Int, val *ethutil.Value) {
+	addr := ethutil.BigToBytes(num, 256)
+	c.state.trie.Update(string(addr), string(val.Encode()))
+}
+
 // Return the gas back to the origin. Used by the Virtual machine or Closures
 func (c *Contract) ReturnGas(val *big.Int, state *State) {
 	c.Amount.Add(c.Amount, val)
diff --git a/ethchain/stack.go b/ethchain/stack.go
index b64b759fd..3c2899e62 100644
--- a/ethchain/stack.go
+++ b/ethchain/stack.go
@@ -237,6 +237,10 @@ func (m *Memory) Get(offset, size int64) []byte {
 	return m.store[offset : offset+size]
 }
 
+func (m *Memory) Len() int {
+	return len(m.store)
+}
+
 func (m *Memory) Print() {
 	fmt.Println("### MEM ###")
 	if len(m.store) > 0 {
diff --git a/ethchain/vm.go b/ethchain/vm.go
index 8b5bb93c0..bc3a9edaf 100644
--- a/ethchain/vm.go
+++ b/ethchain/vm.go
@@ -49,7 +49,7 @@ func (vm *Vm) RunClosure(closure *Closure) []byte {
 	// New stack (should this be shared?)
 	stack := NewStack()
 	// Instruction pointer
-	pc := int64(0)
+	pc := big.NewInt(0)
 	// Current step count
 	step := 0
 	// The base for all big integer arithmetic
@@ -226,7 +226,8 @@ func (vm *Vm) RunClosure(closure *Closure) []byte {
 
 		// 0x50 range
 		case oPUSH: // Push PC+1 on to the stack
-			pc++
+			pc.Add(pc, ethutil.Big1)
+
 			val := closure.GetMem(pc).BigInt()
 			stack.Push(val)
 		case oPOP:
@@ -250,14 +251,22 @@ func (vm *Vm) RunClosure(closure *Closure) []byte {
 			mem.Set(mStart.Int64(), 32, ethutil.BigToBytes(base, 256))
 		case oSLOAD:
 			loc := stack.Pop()
-			val := closure.GetMem(loc.Int64())
+			val := closure.GetMem(loc)
 			stack.Push(val.BigInt())
 		case oSSTORE:
+			val, loc := stack.Popn()
+			closure.SetMem(loc, ethutil.NewValue(val))
 		case oJUMP:
+			pc = stack.Pop()
 		case oJUMPI:
+			pos, cond := stack.Popn()
+			if cond.Cmp(big.NewInt(0)) > 0 {
+				pc = pos
+			}
 		case oPC:
+			stack.Push(pc)
 		case oMSIZE:
-
+			stack.Push(big.NewInt(int64(mem.Len())))
 		// 0x60 range
 		case oCALL:
 			// Pop return size and offset
@@ -304,7 +313,7 @@ func (vm *Vm) RunClosure(closure *Closure) []byte {
 			ethutil.Config.Log.Debugln("Invalid opcode", op)
 		}
 
-		pc++
+		pc.Add(pc, ethutil.Big1)
 	}
 }
 
@@ -682,7 +691,7 @@ func makeInlineTx(addr []byte, value, from, length *big.Int, contract *Contract,
 	j := int64(0)
 	dataItems := make([]string, int(length.Uint64()))
 	for i := from.Int64(); i < length.Int64(); i++ {
-		dataItems[j] = contract.GetMem(j).Str()
+		dataItems[j] = contract.GetMem(big.NewInt(j)).Str()
 		j++
 	}
 
diff --git a/ethutil/common.go b/ethutil/common.go
index 07df6bb13..f15b10e6d 100644
--- a/ethutil/common.go
+++ b/ethutil/common.go
@@ -33,3 +33,9 @@ func CurrencyToString(num *big.Int) string {
 
 	return fmt.Sprintf("%v Wei", num)
 }
+
+var (
+	Big1   = big.NewInt(1)
+	Big0   = big.NewInt(0)
+	Big256 = big.NewInt(0xff)
+)