diff --git a/lib/farm.js b/lib/farm.js
index bdc70e8..a531675 100644
--- a/lib/farm.js
+++ b/lib/farm.js
@@ -2,7 +2,7 @@
 
 const DEFAULT_OPTIONS = {
           maxCallsPerWorker           : Infinity
-        , maxConcurrentWorkers        : require('os').cpus().length
+        , maxConcurrentWorkers        : (require('os').cpus()||{length:1}).length
         , maxConcurrentCallsPerWorker : 10
         , maxConcurrentCalls          : Infinity
         , maxCallTime                 : Infinity // exceed this and the whole worker is terminated