diff --git a/lib/Sys/Linux/Mount.pm b/lib/Sys/Linux/Mount.pm
index d45c883..7efd88a 100644
--- a/lib/Sys/Linux/Mount.pm
+++ b/lib/Sys/Linux/Mount.pm
@@ -50,12 +50,12 @@ our %EXPORT_TAGS = (
 sub mount {
   my ($source, $target, $filesystem, $flags, $options_hr) = @_;
 
-  my $options_str; 
+  my $options_str = ""; 
   if ($options_hr) {
     $options_str = join ',', map {"$_=".$options_hr->{$_}} keys %$options_hr;
   }
 
-  my $ret = _mount_sys($source, $target, $filesystem, $flags//0xc0ed0000, $options_str);
+  my $ret = _mount_sys($source//"", $target//"", $filesystem//"", $flags//0xc0ed0000, $options_str);
 
   if ($ret != 0) {
       croak "mount failed: $ret $!";
diff --git a/lib/Sys/Linux/Namespace.pm b/lib/Sys/Linux/Namespace.pm
index 518f281..af7ddbe 100644
--- a/lib/Sys/Linux/Namespace.pm
+++ b/lib/Sys/Linux/Namespace.pm
@@ -72,7 +72,7 @@ sub post_setup {
     my $data = undef;
     $data = $self->private_tmp if (ref $self->private_tmp eq 'HASH');
 
-    mount("none", "/tmp", "tmpfs", 0, undef);
+    mount("none", "/tmp", "tmpfs", MS_MGC_VAL, undef);
     mount("none", "/tmp", "tmpfs", MS_PRIVATE, $data);
   }
 
@@ -104,14 +104,18 @@ sub run {
   croak "Run must be given a codref to run" unless ref $code eq "CODE";
 
   $self->_subprocess(sub {
-    $self->setup(%args);
+    $self->pre_setup(%args);
+    my $uflags = $self->_uflags;
+    unshare($uflags);
 
     # We've just unshared, if we wanted a private pid space we MUST fork again.
     if ($self->private_pid) {
       $self->_subprocess(sub {
+        $self->post_setup(%args);
         $code->(%args);
       }, %args);
     } else {
+      $self->setup(%args);
       $code->(%args);
     }
   }, %args);
diff --git a/t/02-namespace.t b/t/02-namespace.t
index 45e7d32..7baa09d 100644
--- a/t/02-namespace.t
+++ b/t/02-namespace.t
@@ -6,7 +6,7 @@ use Test::More;
 use Test::SharedFork;
 
 # test 1
-use_ok("Sys::Linux::Namespace");
+use Sys::Linux::Namespace;
 
 # test 2
 SKIP: {