diff --git a/src/gen.ts b/src/gen.ts
index d0bcb20..56321ec 100644
--- a/src/gen.ts
+++ b/src/gen.ts
@@ -1,3 +1,5 @@
+/// <reference path="./typescript.d.ts" />
+
 import * as ts from 'typescript'
 import { OpCode, OpValue, Label } from './opcode'
 import { EnvironmentType } from './types'
@@ -270,6 +272,9 @@ export function gen(code: string): [(OpCode | OpValue)[], VObject[]] {
     switch (binary.operatorToken.kind) {
       case ts.SyntaxKind.EqualsToken:
       case ts.SyntaxKind.PlusEqualsToken:
+      case ts.SyntaxKind.MinusEqualsToken:
+      case ts.SyntaxKind.AsteriskEqualsToken:
+      case ts.SyntaxKind.SlashEqualsToken:
         visitAssignmentExpression(binary as ts.AssignmentExpression<ts.AssignmentOperatorToken>)
         return
     }
@@ -318,13 +323,32 @@ export function gen(code: string): [(OpCode | OpValue)[], VObject[]] {
         break
       }
       case ts.SyntaxKind.PlusEqualsToken:
-        {
-          visitor(expr.right)
-          visitor(expr.left)
-          op.push(OpCode.Add)
-          visitLeftHandSideExpression(expr.left)
-          op.push(OpCode.Set)
-        }
+        visitor(expr.left)
+        visitor(expr.right)
+        op.push(OpCode.Add)
+        visitLeftHandSideExpression(expr.left)
+        op.push(OpCode.Set)
+        break
+      case ts.SyntaxKind.MinusEqualsToken:
+        visitor(expr.left)
+        visitor(expr.right)
+        op.push(OpCode.Sub)
+        visitLeftHandSideExpression(expr.left)
+        op.push(OpCode.Set)
+        break
+      case ts.SyntaxKind.AsteriskEqualsToken:
+        visitor(expr.left)
+        visitor(expr.right)
+        op.push(OpCode.Mul)
+        visitLeftHandSideExpression(expr.left)
+        op.push(OpCode.Set)
+        break
+      case ts.SyntaxKind.SlashEqualsToken:
+        visitor(expr.left)
+        visitor(expr.right)
+        op.push(OpCode.Div)
+        visitLeftHandSideExpression(expr.left)
+        op.push(OpCode.Set)
         break
       default:
         throw new Error('not supported')
diff --git a/tests/gen.test.ts b/tests/gen.test.ts
index 39ebf62..9fb95cd 100644
--- a/tests/gen.test.ts
+++ b/tests/gen.test.ts
@@ -116,10 +116,13 @@ test(`should work with assignment`, () => {
   run(code)
 })
 
-test(`should work with add assignment`, () => {
+test(`should work with add / sub / mul / div assignment`, () => {
   const code = `
-  let a = 1;
-  a += 233;
+  let a = 5;
+  a += 1;
+  a *= 4;
+  a /= 2;
+  a -= 1;
   a  
 `
   run(code)