diff --git a/src/PrusaSlicer.cpp b/src/PrusaSlicer.cpp
index be66d5c54a..be432d487a 100644
--- a/src/PrusaSlicer.cpp
+++ b/src/PrusaSlicer.cpp
@@ -577,7 +577,8 @@ int CLI::run(int argc, char **argv)
 // #ifdef USE_WX
 #if ENABLE_GCODE_VIEWER
         GUI::GUI_App* gui = new GUI::GUI_App(start_as_gcodeviewer ? GUI::GUI_App::EAppMode::GCodeViewer : GUI::GUI_App::EAppMode::Editor);
-        if (gui->get_app_mode() != GUI::GUI_App::EAppMode::GCodeViewer) { // gcode viewer is currently not performing instance check
+        if (gui->get_app_mode() != GUI::GUI_App::EAppMode::GCodeViewer) {
+            // G-code viewer is currently not performing instance check, a new G-code viewer is started every time.
             bool gui_single_instance_setting = gui->app_config->get("single_instance") == "1";
             if (Slic3r::instance_check(argc, argv, gui_single_instance_setting)) {
                 //TODO: do we have delete gui and other stuff?
diff --git a/src/libslic3r/AppConfig.cpp b/src/libslic3r/AppConfig.cpp
index 9b08c086e1..acc8c27c70 100644
--- a/src/libslic3r/AppConfig.cpp
+++ b/src/libslic3r/AppConfig.cpp
@@ -74,7 +74,13 @@ void AppConfig::set_defaults()
 #endif
 
         if (get("single_instance").empty())
-            set("single_instance", "0");
+            set("single_instance", 
+#ifdef __APPLE__
+                "1"
+#else __APPLE__
+                "0"
+#endif __APPLE__
+                );
 
         if (get("remember_output_path").empty())
             set("remember_output_path", "1");
diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 202ead4049..05db7470cc 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -56,7 +56,9 @@ public:
     PrusaSlicerTaskBarIcon(wxTaskBarIconType iconType = wxTBI_DEFAULT_TYPE) : wxTaskBarIcon(iconType) {}
     wxMenu *CreatePopupMenu() override {
         wxMenu *menu = new wxMenu;
-        if(wxGetApp().app_config->get("single_instance") == "1") {
+        if(wxGetApp().app_config->get("single_instance") == "0") {
+            // 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.
             append_menu_item(menu, wxID_ANY, _L("Open new instance"), _L("Open a new PrusaSlicer instance"),
             [this](wxCommandEvent&) { start_new_slicer(); }, "", nullptr);
         }