diff --git a/pkg/vm/context.go b/pkg/vm/context.go
index 6c086249f..cc16ac867 100644
--- a/pkg/vm/context.go
+++ b/pkg/vm/context.go
@@ -72,6 +72,13 @@ type Context struct {
 	retCount int
 }
 
+type contextAux struct {
+	Script string
+	IP     int
+	NextIP int
+	Caller string
+}
+
 // ContextUnloadCallback is a callback method used on context unloading from istack.
 type ContextUnloadCallback func(ctx *Context, commit bool) error
 
@@ -357,3 +364,14 @@ func (c *Context) HasTryBlock() bool {
 	}
 	return false
 }
+
+// MarshalJSON implements the JSON marshalling interface.
+func (c *Context) MarshalJSON() ([]byte, error) {
+	var aux = contextAux{
+		Script: c.ScriptHash().StringLE(),
+		IP:     c.ip,
+		NextIP: c.nextip,
+		Caller: c.sc.callingScriptHash.StringLE(),
+	}
+	return json.Marshal(aux)
+}
diff --git a/pkg/vm/vm.go b/pkg/vm/vm.go
index 3a348d530..7cc768d0f 100644
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@@ -335,18 +335,19 @@ func (v *VM) loadScriptWithCallingHash(b []byte, exe *nef.File, caller util.Uint
 	hash util.Uint160, f callflag.CallFlag, rvcount int, offset int, onContextUnload ContextUnloadCallback) {
 	v.checkInvocationStackSize()
 	ctx := NewContextWithParams(b, rvcount, offset)
+	parent := v.Context()
+	if parent != nil {
+		ctx.sc.callingContext = parent.sc
+		parent.sc.estack = v.estack
+	}
 	if rvcount != -1 || v.estack.Len() != 0 {
 		v.estack = subStack(v.estack)
 	}
-	parent := v.Context()
 	ctx.sc.estack = v.estack
 	initStack(&ctx.tryStack, "exception", nil)
 	ctx.sc.callFlag = f
 	ctx.sc.scriptHash = hash
 	ctx.sc.callingScriptHash = caller
-	if parent != nil {
-		ctx.sc.callingContext = parent.sc
-	}
 	ctx.sc.NEF = exe
 	if v.invTree != nil {
 		curTree := v.invTree
@@ -381,7 +382,8 @@ func (v *VM) PopResult() interface{} {
 
 // DumpIStack returns json formatted representation of the invocation stack.
 func (v *VM) DumpIStack() string {
-	return dumpStack(&v.istack)
+	b, _ := json.MarshalIndent(v.istack.ToArray(), "", "    ")
+	return string(b)
 }
 
 // DumpEStack returns json formatted representation of the execution stack.