diff --git a/README.md b/README.md
index 19787a9..1deb9b4 100644
--- a/README.md
+++ b/README.md
@@ -49,9 +49,9 @@ Use the applicable instructions for the interface of your choice (currently limi
 The [command-line interface](http://en.wikipedia.org/wiki/Command-line_interface) does not have a graphical component and is ideal for automation purposes and headless machines. The interface can run using a sequence of series addresses (the site address containing the chapter listing), or with a batch-mode source file. The `mangarack --help` command will produce the following output:
 
     Usage: mangarack [options]
-    
+
     Options:
-    
+
       -h, --help           output usage information
       -V, --version        output the version number
       -a, --animation      Disable image animation framing.
@@ -120,7 +120,7 @@ Download *Aoi Hana* from *MangaFox* and *Citrus* from *Batoto* to the current wo
 * `-o <s> or --output <s>` sets the output directory (defaults to *current work directory*).
 * `-s <s> or --source <s>` sets the batch-mode source file (defaults to *MangaRack.txt*)
 * `-t <s> or --transform <s>` sets an overriding image format transformation (e.g. *jpg*).
-* `-w <s> or --workers <s>` sets the maximum concurrency (defaults to the machines cores).
+* `-w <s> or --workers <s>` sets the maximum concurrency (defaults to # of cores, up to 4).
 
 ## Developers
 
diff --git a/lib/cli/index.js b/lib/cli/index.js
index 77f1bf6..be3c606 100644
--- a/lib/cli/index.js
+++ b/lib/cli/index.js
@@ -13,7 +13,7 @@ var parse = require('./parse');
   var options = parse(process.argv);
   _initialize(options, options.source || defaultSource, function(err, tasks) {
     if (err) return console.error(err.stack || err);
-    var maximum = options.workers || os.cpus().length;
+    var maximum = options.workers || _getNumberOfCores();
     nodejs(tasks, maximum).on('data', function(data) {
       console.log(_pretty(data));
     }).on('error', function(err) {
@@ -38,6 +38,16 @@ function _calculate(timeInMs) {
   return '(' + hours + ':' + minutes + ':' + seconds + ')';
 }
 
+/**
+ * Gets the number of cores, limited to a maximum of 4.
+ * @returns {number}
+ */
+function _getNumberOfCores() {
+  var numberOfCores = os.cpus().length;
+  if (numberOfCores > 4) return 4;
+  return numberOfCores;
+}
+
 /**
  * Initializes the tasks.
  * @private
diff --git a/package.json b/package.json
index bbceebc..245227c 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
   ],
   "name": "mangarack",
   "repository": "git://github.com/Deathspike/mangarack.js.git",
-  "version": "3.1.6",
+  "version": "3.1.7",
   "bin": {
     "mangarack": "./bin/mangarack"
   },