diff --git a/pkg/vm/stack.go b/pkg/vm/stack.go
index fca28215b..659ff0191 100644
--- a/pkg/vm/stack.go
+++ b/pkg/vm/stack.go
@@ -162,13 +162,15 @@ func NewStack(n string) *Stack {
 }
 
 func newStack(n string, refc *refCounter) *Stack {
-	s := &Stack{
-		name: n,
-		refs: refc,
-	}
+	s := new(Stack)
+	initStack(s, n, refc)
+	return s
+}
+func initStack(s *Stack, n string, refc *refCounter) {
+	s.name = n
+	s.refs = refc
 	s.top.next = &s.top
 	s.top.prev = &s.top
-	return s
 }
 
 // Clear clears all elements on the stack and set its length to 0.
diff --git a/pkg/vm/vm.go b/pkg/vm/vm.go
index 9fe81d69d..4856270e4 100644
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@@ -68,7 +68,7 @@ type VM struct {
 	// callback to get interop price
 	getPrice func(opcode.Opcode, []byte) int64
 
-	istack *Stack // invocation stack.
+	istack Stack  // invocation stack.
 	estack *Stack // execution stack.
 
 	uncaughtException stackitem.Item // exception being handled
@@ -99,7 +99,6 @@ func New() *VM {
 func NewWithTrigger(t trigger.Type) *VM {
 	vm := &VM{
 		state:   NoneState,
-		istack:  newStack("invocation", nil),
 		trigger: t,
 
 		SyscallHandler: defaultSyscallHandler,
@@ -107,6 +106,7 @@ func NewWithTrigger(t trigger.Type) *VM {
 	}
 
 	vm.refs.items = make(map[stackitem.Item]int)
+	initStack(&vm.istack, "invocation", nil)
 	vm.estack = newStack("evaluation", &vm.refs)
 	return vm
 }
@@ -135,7 +135,7 @@ func (v *VM) Estack() *Stack {
 
 // Istack returns the invocation stack so interop hooks can utilize this.
 func (v *VM) Istack() *Stack {
-	return v.istack
+	return &v.istack
 }
 
 // LoadArgs loads in the arguments used in the Mian entry point.
@@ -340,7 +340,7 @@ func (v *VM) PopResult() interface{} {
 func (v *VM) Stack(n string) string {
 	var s *Stack
 	if n == "istack" {
-		s = v.istack
+		s = &v.istack
 	}
 	if n == "estack" {
 		s = v.estack
@@ -1786,7 +1786,7 @@ func (v *VM) GetCallingScriptHash() util.Uint160 {
 
 // GetEntryScriptHash implements ScriptHashGetter interface.
 func (v *VM) GetEntryScriptHash() util.Uint160 {
-	return v.getContextScriptHash(v.Istack().Len() - 1)
+	return v.getContextScriptHash(v.istack.len - 1)
 }
 
 // GetCurrentScriptHash implements ScriptHashGetter interface.