diff --git a/lib/Sys/Linux/Mount.pm b/lib/Sys/Linux/Mount.pm
index d249d54..9b2cae7 100644
--- a/lib/Sys/Linux/Mount.pm
+++ b/lib/Sys/Linux/Mount.pm
@@ -22,7 +22,7 @@ sub mount {
 
     my $options_str = join ',', map {"$_=".$options_hr->{$_}} keys %$options_hr;
 
-    my $ret = _mount_sys($source, $target, $filesystem//undef, $flags, $options_str);
+    my $ret = _mount_sys($source//"", $target//"", $filesystem//"", $flags//0, $options_str//"");
 
     if ($ret != 0) {
         die "mount failed: $ret $!";
diff --git a/lib/Sys/Linux/Namespace.pm b/lib/Sys/Linux/Namespace.pm
index 5f15062..ce02b5b 100644
--- a/lib/Sys/Linux/Namespace.pm
+++ b/lib/Sys/Linux/Namespace.pm
@@ -85,7 +85,9 @@ sub namespace {
     } else {
         unshare($uflags);
         $post_setup->();
-    }
+    };
+
+    return 1;
 }
 
 1;