1 files changed, 18 insertions, 2 deletions
diff --git a/lib/vm.js b/lib/vm.js
index 5266dbd29f..ca7b6f3396 100644
--- a/lib/vm.js
+++ b/lib/vm.js
@@ -26,10 +26,13 @@ const {
   kParsingContext,
 
   makeContext,
-  isContext,
+  isContext: _isContext,
 } = process.binding('contextify');
 
-const { ERR_INVALID_ARG_TYPE } = require('internal/errors').codes;
+const {
+  ERR_INVALID_ARG_TYPE,
+  ERR_MISSING_ARGS
+} = require('internal/errors').codes;
 
 // The binding provides a few useful primitives:
 // - Script(code, { filename = "evalmachine.anonymous",
@@ -119,6 +122,19 @@ function getContextOptions(options) {
   return {};
 }
 
+function isContext(sandbox) {
+  if (arguments.length < 1) {
+    throw new ERR_MISSING_ARGS('sandbox');
+  }
+
+  if (typeof sandbox !== 'object' && typeof sandbox !== 'function' ||
+      sandbox === null) {
+    throw new ERR_INVALID_ARG_TYPE('sandbox', 'object', sandbox);
+  }
+
+  return _isContext(sandbox);
+}
+
 let defaultContextNameIndex = 1;
 function createContext(sandbox, options) {
   if (sandbox === undefined) {