diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 05db7470c..ba1fd56c7 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -56,9 +56,10 @@ public:
     PrusaSlicerTaskBarIcon(wxTaskBarIconType iconType = wxTBI_DEFAULT_TYPE) : wxTaskBarIcon(iconType) {}
     wxMenu *CreatePopupMenu() override {
         wxMenu *menu = new wxMenu;
-        if(wxGetApp().app_config->get("single_instance") == "0") {
+        if(wxGetApp().app_config->get("single_instance") == "1") {
             // Only allow opening a new PrusaSlicer instance on OSX if "single_instance" is disabled, 
             // as starting new instances would interfere with the locking mechanism of "single_instance" support.
+            //FIXME Vojtech thinks the condition is wrong.
             append_menu_item(menu, wxID_ANY, _L("Open new instance"), _L("Open a new PrusaSlicer instance"),
             [this](wxCommandEvent&) { start_new_slicer(); }, "", nullptr);
         }