diff --git a/lib/ProcessContainerFork.js b/lib/ProcessContainerFork.js
index ffb1d253..c612adb6 100644
--- a/lib/ProcessContainerFork.js
+++ b/lib/ProcessContainerFork.js
@@ -60,8 +60,10 @@ if (process.env.uid || process.env.gid) {
     if (process.env.gid)
       process.setgid(process.env.gid);
     if (process.env.uid){
-      process.initgroups(process.env.uid, process.env.uid);
-      process.setgid(process.env.uid);
+      // If no gid specified - set gid to uid
+      var new_gid = process.env.gid == null ? process.env.uid : process.env.gid; 
+      process.initgroups(process.env.uid, new_gid);
+      process.setgid(new_gid);
       process.setuid(process.env.uid);
     }
   } catch(e) {