diff --git a/lib/Slic3r/GUI.pm b/lib/Slic3r/GUI.pm
index c65793d4b..2dc560cad 100644
--- a/lib/Slic3r/GUI.pm
+++ b/lib/Slic3r/GUI.pm
@@ -52,6 +52,8 @@ use constant FILE_WILDCARDS => {
 };
 use constant MODEL_WILDCARD => join '|', @{&FILE_WILDCARDS}{qw(known stl obj amf prusa)};
 
+# Datadir provided on the command line.
+our $datadir;
 # If set, the "Controller" tab for the control of the printer over serial line and the serial port settings are hidden.
 our $no_plater;
 our @cb;
@@ -71,6 +73,12 @@ sub OnInit {
     $self->SetAppName('Slic3r');
     $self->SetAppDisplayName('Slic3r Prusa Edition');
     Slic3r::debugf "wxWidgets version %s, Wx version %s\n", &Wx::wxVERSION_STRING, $Wx::VERSION;
+
+    # Set the Slic3r data directory at the Slic3r XS module.
+    # Unix: ~/.Slic3r
+    # Windows: "C:\Users\username\AppData\Roaming\Slic3r" or "C:\Documents and Settings\username\Application Data\Slic3r"
+    # Mac: "~/Library/Application Support/Slic3r"
+    Slic3r::set_data_dir($datadir || Wx::StandardPaths::Get->GetUserDataDir);
     
     $self->{notifier} = Slic3r::GUI::Notifier->new;
     $self->{app_config} = Slic3r::GUI::AppConfig->new;
diff --git a/slic3r.pl b/slic3r.pl
index 87c8fe40c..e49457c20 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -100,17 +100,12 @@ if ($opt{save}) {
 my $config = Slic3r::Config::new_from_defaults;
 $config->apply($cli_config);
 
-# locate or create data directory
-# Unix: ~/.Slic3r
-# Windows: "C:\Users\username\AppData\Roaming\Slic3r" or "C:\Documents and Settings\username\Application Data\Slic3r"
-# Mac: "~/Library/Application Support/Slic3r"
-Slic3r::set_data_dir($opt{datadir} || Wx::StandardPaths::Get->GetUserDataDir);
-
 # launch GUI
 my $gui;
 if ((!@ARGV || $opt{gui}) && !$opt{save} && eval "require Slic3r::GUI; 1") {
     {
         no warnings 'once';
+        $Slic3r::GUI::datadir       = Slic3r::decode_path($opt{datadir} // '');
         $Slic3r::GUI::no_controller = $opt{no_controller};
         $Slic3r::GUI::no_plater     = $opt{no_plater};
         $Slic3r::GUI::autosave      = $opt{autosave};