diff --git a/src/server.js b/src/server.js
index 8e551f7891..54a7ad9422 100644
--- a/src/server.js
+++ b/src/server.js
@@ -7,12 +7,11 @@ utils.setupConfig();
 var logging = require('./logging');
 var isProd = nconf.get('NODE_ENV') === 'production';
 var isDev = nconf.get('NODE_ENV') === 'development';
+var cores = +nconf.get("CORES");
 
-if (cluster.isMaster && (isDev || isProd)) {
+if (cores!==0 && cluster.isMaster && (isDev || isProd)) {
   // Fork workers. If config.json has CORES=x, use that - otherwise, use all cpus-1 (production)
-  var cpus = require('os').cpus(),
-    cores = +nconf.get("CORES");
-  _.times(cores || cpus.length-1, cluster.fork);
+  _.times(cores || require('os').cpus().length-1, cluster.fork);
 
   cluster.on('disconnect', function(worker, code, signal) {
     var w = cluster.fork(); // replace the dead worker