diff --git a/lib/__tests__/cloudworker.test.js b/lib/__tests__/cloudworker.test.js
index e1b96b1..7491354 100644
--- a/lib/__tests__/cloudworker.test.js
+++ b/lib/__tests__/cloudworker.test.js
@@ -11,6 +11,11 @@ describe('cloudworker', () => {
     expect(() => { new Cloudworker(12) }).toThrow(new TypeError('worker script must be a string')) // eslint-disable-line no-new
   })
 
+  test('throws on eval', async () => {
+    const bindings = { EvalError: EvalError }
+    expect(() => { new Cloudworker(`eval('true')`, { bindings }) }).toThrow(new EvalError('Code generation from strings disallowed for this context')) // eslint-disable-line no-new
+  })
+
   test('log does nothing if debug is false', async () => {
     const cw = new Cloudworker(simpleScript)
     global.console = {error: jest.fn(), log: jest.fn()}
diff --git a/lib/__tests__/runtime.test.js b/lib/__tests__/runtime.test.js
index 3de5317..1b7d7a2 100644
--- a/lib/__tests__/runtime.test.js
+++ b/lib/__tests__/runtime.test.js
@@ -100,8 +100,8 @@ describe('runtime', () => {
   test('instanceof from different realm works', () => {
     const dummyFactory = Symbol('dummy factory')
     const bindings = {
-      instanceOfObject: (obj) => { return obj instanceof Object },
-      isArrayBufferView: (ab) => { return ArrayBuffer.isView(ab) },
+      instanceOfObject (obj) { return obj instanceof Object },
+      isArrayBufferView (ab) { return ArrayBuffer.isView(ab) },
     }
     const context = new runtime.Context(() => {}, dummyFactory, bindings)
 
@@ -111,4 +111,17 @@ describe('runtime', () => {
     expect(objTest).toEqual(true)
     expect(arrayBufferViewTest).toEqual(true)
   })
+
+  test('object binding can be disabled across realms', () => {
+    const dummyFactory = Symbol('dummy factory')
+    const bindings = {
+      VM_DEFAULT_REALM: true,
+      instanceOfObject (obj) { return obj instanceof Object },
+    }
+    const context = new runtime.Context(() => {}, dummyFactory, bindings)
+
+    const objTest = vm.runInNewContext('instanceOfObject(new Object())', context)
+
+    expect(objTest).toEqual(false)
+  })
 })
diff --git a/lib/runtime.js b/lib/runtime.js
index cfb1e0f..24c5d64 100644
--- a/lib/runtime.js
+++ b/lib/runtime.js
@@ -30,65 +30,67 @@ class Context {
     this.atob = atob
     this.btoa = btoa
 
-    // These are necessary to use "instanceof" within a vm
-    this.Array = Array
-    this.ArrayBuffer = ArrayBuffer
-    this.Atomics = Atomics
-    this.BigInt = BigInt
-    this.BigInt64Array = BigInt64Array
-    this.BigUint64Array = BigUint64Array
-    this.Boolean = Boolean
-    this.DataView = DataView
-    this.Date = Date
-    this.Error = Error
-    this.EvalError = EvalError
-    this.Float32Array = Float32Array
-    this.Float64Array = Float64Array
-    this.Function = Function
-    this.Int8Array = Int8Array
-    this.Int16Array = Int16Array
-    this.Int32Array = Int32Array
-    this.Intl = Intl
-    this.JSON = JSON
-    this.Map = Map
-    this.Math = Math
-    this.NaN = NaN
-    this.Number = Number
-    this.Object = Object
-    this.Promise = Promise
-    this.Proxy = Proxy
-    this.RangeError = RangeError
-    this.ReferenceError = ReferenceError
-    this.Reflect = Reflect
-    this.RegExp = RegExp
-    this.Set = Set
-    this.SharedArrayBuffer = SharedArrayBuffer
-    this.String = String
-    this.Symbol = Symbol
-    this.SyntaxError = SyntaxError
-    this.TypeError = TypeError
-    this.URIError = URIError
-    this.Uint8Array = Uint8Array
-    this.Uint8ClampedArray = Uint8ClampedArray
-    this.Uint16Array = Uint16Array
-    this.Uint32Array = Uint32Array
-    this.WeakMap = WeakMap
-    this.WebAssembly = WebAssembly
-    this.console = console
-    this.constructor = constructor
-    this.decodeURI = decodeURI
-    this.decodeURIComponent = decodeURIComponent
-    this.encodeURI = encodeURI
-    this.encodeURIComponent = encodeURIComponent
-    this.escape = escape
-    this.globalThis = this
-    this.isFinite = isFinite
-    this.isNaN = isNaN
-    this.parseFloat = parseFloat
-    this.parseInt = parseInt
-    this.self = this
-    this.undefined = undefined
-    this.unescape = unescape
+    // These are necessary to use "instanceof" within a vm accross different realms
+    if (!bindings.VM_DEFAULT_REALM) {
+      this.Array = Array
+      this.ArrayBuffer = ArrayBuffer
+      this.Atomics = Atomics
+      this.BigInt = BigInt
+      this.BigInt64Array = BigInt64Array
+      this.BigUint64Array = BigUint64Array
+      this.Boolean = Boolean
+      this.DataView = DataView
+      this.Date = Date
+      this.Error = Error
+      this.EvalError = EvalError
+      this.Float32Array = Float32Array
+      this.Float64Array = Float64Array
+      this.Function = Function
+      this.Int8Array = Int8Array
+      this.Int16Array = Int16Array
+      this.Int32Array = Int32Array
+      this.Intl = Intl
+      this.JSON = JSON
+      this.Map = Map
+      this.Math = Math
+      this.NaN = NaN
+      this.Number = Number
+      this.Object = Object
+      this.Promise = Promise
+      this.Proxy = Proxy
+      this.RangeError = RangeError
+      this.ReferenceError = ReferenceError
+      this.Reflect = Reflect
+      this.RegExp = RegExp
+      this.Set = Set
+      this.SharedArrayBuffer = SharedArrayBuffer
+      this.String = String
+      this.Symbol = Symbol
+      this.SyntaxError = SyntaxError
+      this.TypeError = TypeError
+      this.URIError = URIError
+      this.Uint8Array = Uint8Array
+      this.Uint8ClampedArray = Uint8ClampedArray
+      this.Uint16Array = Uint16Array
+      this.Uint32Array = Uint32Array
+      this.WeakMap = WeakMap
+      this.WebAssembly = WebAssembly
+      this.console = console
+      this.constructor = constructor
+      this.decodeURI = decodeURI
+      this.decodeURIComponent = decodeURIComponent
+      this.encodeURI = encodeURI
+      this.encodeURIComponent = encodeURIComponent
+      this.escape = escape
+      this.globalThis = this
+      this.isFinite = isFinite
+      this.isNaN = isNaN
+      this.parseFloat = parseFloat
+      this.parseInt = parseInt
+      this.self = this
+      this.undefined = undefined
+      this.unescape = unescape
+    }
 
     Object.assign(this, bindings)
   }