diff --git a/package-lock.json b/package-lock.json
index 3cca706bd..3ea3c3e54 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "shelljs",
-  "version": "0.8.3",
+  "version": "0.8.4",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index fcb0fb570..b52070538 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "shelljs",
-  "version": "0.8.3",
+  "version": "0.8.4",
   "description": "Portable Unix shell commands for Node.js",
   "keywords": [
     "shelljs",
diff --git a/src/common.js b/src/common.js
index 14a49fc58..64fa2fbc0 100644
--- a/src/common.js
+++ b/src/common.js
@@ -450,7 +450,7 @@ function _register(name, implementation, wrapOptions) {
   // If an option isn't specified, use the default
   wrapOptions = Object.assign({}, DEFAULT_WRAP_OPTIONS, wrapOptions);
 
-  if (shell[name]) {
+  if (shell.hasOwnProperty(name)) {
     throw new Error('Command `' + name + '` already exists');
   }