diff --git a/lib/chrome.js b/lib/chrome.js
index 18cc6fa..5da15df 100644
--- a/lib/chrome.js
+++ b/lib/chrome.js
@@ -27,8 +27,8 @@ var ChromeObject = function() {
     this.binPath = null;
 
     this.profileName = "Default";
-    this.userDataDir = null;
-    this.defaultUserDataDir = null;
+    this.userDataDir = null;  // Default set to null after 0.2.7.54; change via .setUserDataDir.
+    this.defaultUserDataDir = null;  // Set by .setPublisherName; not frequently referenced.
     this.installedDir = "Chrome";
 
     // proxy
@@ -198,7 +198,12 @@ var ChromeObject = function() {
         }
 
         cmd.push("\"--profile-directory=" + this.profileName + "\"");
-        cmd.push("\"--user-data-dir=" + this.userDataDir + "\"");
+        
+        // set user data directory
+        if (this.userDataDir != null) {
+            cmd.push("\"--user-data-dir=" + this.userDataDir + "\"");
+        }
+        
         cmd.push("\"" + url + "\"");
 
         SHELL.createShoutcut(publisherName.get() + " (" + this.profileName + ")", cmd.join(' '), SYS.getCurrentScriptDirectory());
@@ -300,7 +305,9 @@ var ChromeObject = function() {
             }
 
             // set user data directory
-            cmd.push("\"--user-data-dir=" + this.userDataDir + "\"");
+            if (this.userDataDir != null) {
+                cmd.push("\"--user-data-dir=" + this.userDataDir + "\"");
+            }
 
             // choice user agent
             if (this.userAgent == null && this.userAgents.length > 0) {
@@ -1446,7 +1453,7 @@ exports.startDebugInPrivate = function(url, proxy, profileName, debuggingPort, i
 
 exports.publisherName = publisherName;
 
-exports.VERSIONINFO = "Chrome Web Browser Debugging Interface (chrome.js) version 0.4.21";
+exports.VERSIONINFO = "Chrome Web Browser Debugging Interface (chrome.js) version 0.4.22";
 exports.AUTHOR = "abuse@catswords.net";
 exports.global = global;
 exports.require = global.require;