diff --git a/ethchain/closure.go b/ethchain/closure.go
index 5c508179e..defd8b5c8 100644
--- a/ethchain/closure.go
+++ b/ethchain/closure.go
@@ -8,7 +8,7 @@ import (
 )
 
 type Callee interface {
-	ReturnGas(*big.Int, *State)
+	ReturnGas(*big.Int, *big.Int, *State)
 	Address() []byte
 }
 
@@ -83,18 +83,16 @@ func (c *Closure) Return(ret []byte) []byte {
 	// If no callee is present return it to
 	// the origin (i.e. contract or tx)
 	if c.callee != nil {
-		c.callee.ReturnGas(c.Gas, c.State)
+		c.callee.ReturnGas(c.Gas, c.Price, c.State)
 	} else {
-		c.object.ReturnGas(c.Gas, c.State)
-		// TODO incase it's a POST contract we gotta serialise the contract again.
-		// But it's not yet defined
+		c.object.ReturnGas(c.Gas, c.Price, c.State)
 	}
 
 	return ret
 }
 
 // Implement the Callee interface
-func (c *Closure) ReturnGas(gas *big.Int, state *State) {
+func (c *Closure) ReturnGas(gas, price *big.Int, state *State) {
 	// Return the gas to the closure
 	c.Gas.Add(c.Gas, gas)
 }
diff --git a/ethchain/state_object.go b/ethchain/state_object.go
index 8b4de0c4f..f562e5b04 100644
--- a/ethchain/state_object.go
+++ b/ethchain/state_object.go
@@ -1,6 +1,7 @@
 package ethchain
 
 import (
+	"fmt"
 	"github.com/ethereum/eth-go/ethutil"
 	"math/big"
 )
@@ -70,8 +71,9 @@ func (c *StateObject) SetMem(num *big.Int, val *ethutil.Value) {
 }
 
 // Return the gas back to the origin. Used by the Virtual machine or Closures
-func (c *StateObject) ReturnGas(val *big.Int, state *State) {
-	c.AddAmount(val)
+func (c *StateObject) ReturnGas(gas, price *big.Int, state *State) {
+	remainder := new(big.Int).Mul(gas, price)
+	c.AddAmount(remainder)
 }
 
 func (c *StateObject) AddAmount(amount *big.Int) {
@@ -82,18 +84,33 @@ func (c *StateObject) SubAmount(amount *big.Int) {
 	c.Amount.Sub(c.Amount, amount)
 }
 
+func (c *StateObject) ConvertGas(gas, price *big.Int) error {
+	total := new(big.Int).Mul(gas, price)
+	if total.Cmp(c.Amount) > 0 {
+		return fmt.Errorf("insufficient amount: %v, %v", c.Amount, total)
+	}
+
+	c.SubAmount(total)
+
+	return nil
+}
+
+// Returns the address of the contract/account
 func (c *StateObject) Address() []byte {
 	return c.address
 }
 
+// Returns the main script body
 func (c *StateObject) Script() []byte {
 	return c.script
 }
 
+// Returns the initialization script
 func (c *StateObject) Init() []byte {
 	return c.initScript
 }
 
+// State object encoding methods
 func (c *StateObject) RlpEncode() []byte {
 	var root interface{}
 	if c.state != nil {
@@ -113,6 +130,7 @@ func (c *StateObject) RlpDecode(data []byte) {
 	c.script = decoder.Get(3).Bytes()
 }
 
+// Converts an transaction in to a state object
 func MakeContract(tx *Transaction, state *State) *StateObject {
 	// Create contract if there's no recipient
 	if tx.IsContract() {
diff --git a/ethchain/vm.go b/ethchain/vm.go
index 85aefa685..c249adfeb 100644
--- a/ethchain/vm.go
+++ b/ethchain/vm.go
@@ -102,10 +102,9 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 			}
 		*/
 
-		// TODO Get each instruction cost properly
 		gas := new(big.Int)
 		useGas := func(amount *big.Int) {
-			gas.Add(gas, new(big.Int).Mul(amount, closure.Price))
+			gas.Add(gas, amount)
 		}
 
 		switch op {
@@ -142,6 +141,8 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 
 			return closure.Return(nil), fmt.Errorf("insufficient gas %v %v", closure.Gas, gas)
 		}
+
+		// Sub the amount of gas from the remaining
 		closure.Gas.Sub(closure.Gas, gas)
 
 		switch op {
@@ -157,7 +158,6 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 			x, y := stack.Popn()
 			// (x + y) % 2 ** 256
 			base.Add(x, y)
-			base.Mod(base, Pow256)
 			// Pop result back on the stack
 			stack.Push(base)
 		case oSUB:
@@ -165,7 +165,6 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 			x, y := stack.Popn()
 			// (x - y) % 2 ** 256
 			base.Sub(x, y)
-			base.Mod(base, Pow256)
 			// Pop result back on the stack
 			stack.Push(base)
 		case oMUL:
@@ -173,7 +172,6 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 			x, y := stack.Popn()
 			// (x * y) % 2 ** 256
 			base.Mul(x, y)
-			base.Mod(base, Pow256)
 			// Pop result back on the stack
 			stack.Push(base)
 		case oDIV:
@@ -325,7 +323,7 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 		case oCALLDATASIZE:
 			stack.Push(big.NewInt(int64(len(closure.Args))))
 		case oGASPRICE:
-			// TODO
+			stack.Push(closure.Price)
 
 			// 0x40 range
 		case oPREVHASH:
@@ -339,7 +337,8 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 		case oDIFFICULTY:
 			stack.Push(vm.vars.Diff)
 		case oGASLIMIT:
-		// TODO
+			// TODO
+			stack.Push(big.NewInt(0))
 
 		// 0x50 range
 		case oPUSH: // Push PC+1 on to the stack
@@ -399,11 +398,14 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 		case oJUMP:
 			require(1)
 			pc = stack.Pop()
+			// Reduce pc by one because of the increment that's at the end of this for loop
+			pc.Sub(pc, ethutil.Big1)
 		case oJUMPI:
 			require(2)
 			cond, pos := stack.Popn()
 			if cond.Cmp(ethutil.BigTrue) == 0 {
 				pc = pos
+				pc.Sub(pc, ethutil.Big1)
 			}
 		case oPC:
 			stack.Push(pc)
@@ -421,21 +423,39 @@ func (vm *Vm) RunClosure(closure *Closure, hook DebugHook) (ret []byte, err erro
 			inSize, inOffset := stack.Popn()
 			// Pop return size and offset
 			retSize, retOffset := stack.Popn()
+			// Make sure there's enough gas
+			if closure.Gas.Cmp(gas) < 0 {
+				stack.Push(ethutil.BigFalse)
+
+				break
+			}
 			// Get the arguments from the memory
 			args := mem.Get(inOffset.Int64(), inSize.Int64())
 			// Fetch the contract which will serve as the closure body
 			contract := vm.state.GetContract(addr.Bytes())
-			// Create a new callable closure
-			closure := NewClosure(closure, contract, contract.script, vm.state, gas, closure.Price, value)
-			// Executer the closure and get the return value (if any)
-			ret, err := closure.Call(vm, args, hook)
-			if err != nil {
-				stack.Push(ethutil.BigFalse)
-			} else {
-				stack.Push(ethutil.BigTrue)
-			}
 
-			mem.Set(retOffset.Int64(), retSize.Int64(), ret)
+			if contract != nil {
+				// Prepay for the gas
+				// If gas is set to 0 use all remaining gas for the next call
+				if gas.Cmp(big.NewInt(0)) == 0 {
+					gas = closure.Gas
+				}
+				closure.Gas.Sub(closure.Gas, gas)
+				// Create a new callable closure
+				closure := NewClosure(closure, contract, contract.script, vm.state, gas, closure.Price, value)
+				// Executer the closure and get the return value (if any)
+				ret, err := closure.Call(vm, args, hook)
+				if err != nil {
+					stack.Push(ethutil.BigFalse)
+				} else {
+					stack.Push(ethutil.BigTrue)
+				}
+
+				mem.Set(retOffset.Int64(), retSize.Int64(), ret)
+			} else {
+				ethutil.Config.Log.Debugf("Contract %x not found\n", addr.Bytes())
+				stack.Push(ethutil.BigFalse)
+			}
 		case oRETURN:
 			require(2)
 			size, offset := stack.Popn()
diff --git a/ethchain/vm_test.go b/ethchain/vm_test.go
index f66f2a896..cca9b876a 100644
--- a/ethchain/vm_test.go
+++ b/ethchain/vm_test.go
@@ -86,9 +86,9 @@ func TestRun4(t *testing.T) {
 		int32 a = 10
 		int32 b = 20
 		if a > b {
-			int32 c = this.caller()
+			int32 c = this.Caller()
 		}
-		exit()
+		Exit()
 	`), false)
 	script := ethutil.Assemble(asm...)
 	tx := NewContractCreationTx(ethutil.Big("0"), ethutil.Big("1000"), script, nil)
@@ -103,8 +103,9 @@ func TestRun4(t *testing.T) {
 			store[1000] = 10^20
 		}
 
-		store[1001] = this.value() * 20
-		store[this.origin()] = store[this.origin()] + 1000
+
+		store[1001] = this.Value() * 20
+		store[this.Origin()] = store[this.Origin()] + 1000
 
 		if store[1001] > 20 {
 			store[1001] = 10^50
@@ -112,8 +113,18 @@ func TestRun4(t *testing.T) {
 
 		int8 ret = 0
 		int8 arg = 10
-		store[1002] = "a46df28529eb8aa8b8c025b0b413c5f4b688352f"
-		call(store[1002], 0, 100000000, arg, ret)
+		Call(0xe6a12555fad1fb6eaaaed69001a87313d1fd7b54, 0, 100, arg, ret)
+
+		big t
+		for int8 i = 0; i < 10; i++ {
+			t = i
+		}
+
+		if 10 > 20 {
+			int8 shouldnt = 2
+		} else {
+			int8 should = 1
+		}
 	`), false)
 	if err != nil {
 		fmt.Println(err)
@@ -125,10 +136,17 @@ func TestRun4(t *testing.T) {
 	callerTx := NewContractCreationTx(ethutil.Big("0"), ethutil.Big("1000"), callerScript, nil)
 
 	// Contract addr as test address
+	gas := big.NewInt(1000)
+	gasPrice := big.NewInt(10)
 	account := NewAccount(ContractAddr, big.NewInt(10000000))
-	fmt.Println(account)
+	fmt.Println("account.Amount =", account.Amount)
 	c := MakeContract(callerTx, state)
-	callerClosure := NewClosure(account, c, c.script, state, big.NewInt(1000000000), big.NewInt(10), big.NewInt(0))
+	e := account.ConvertGas(gas, gasPrice)
+	if e != nil {
+		fmt.Println(err)
+	}
+	fmt.Println("account.Amount =", account.Amount)
+	callerClosure := NewClosure(account, c, c.script, state, gas, gasPrice, big.NewInt(0))
 
 	vm := NewVm(state, RuntimeVars{
 		Origin:      account.Address(),
@@ -138,11 +156,11 @@ func TestRun4(t *testing.T) {
 		Time:        1,
 		Diff:        big.NewInt(256),
 	})
-	_, e := callerClosure.Call(vm, nil, nil)
+	_, e = callerClosure.Call(vm, nil, nil)
 	if e != nil {
 		fmt.Println("error", e)
 	}
-	fmt.Println(account)
+	fmt.Println("account.Amount =", account.Amount)
 }
 
 func TestRun5(t *testing.T) {
@@ -156,6 +174,5 @@ func TestRun5(t *testing.T) {
 		}
 		exit()
 	`), false)
-	script := ethutil.Assemble(asm...)
-	fmt.Println(Disassemble(script))
+	ethutil.Assemble(asm...)
 }