--- a/node/lib/Munin/Node/Service.pm
+++ b/node/lib/Munin/Node/Service.pm
@@ -225,7 +225,11 @@ sub change_real_and_effective_user_and_group
 
             print STDERR "# Setting /egid/euid/ to /$egids/$uid/\n"
                 if $config->{DEBUG};
-            Munin::Node::OS->set_effective_group_id($egids) unless $rgid == $root_gid;
+            if ($rgid != $root_gid) {
+                for my $egid (split(/ /, $egids)) {
+                    Munin::Node::OS->set_effective_group_id($egid);
+                }
+            }
             Munin::Node::OS->set_effective_user_id($uid)    unless $uid  == $root_uid;
         };