diff --git a/src/slic3r/GUI/MainFrame.cpp b/src/slic3r/GUI/MainFrame.cpp
index 858744229c..a5a920f825 100644
--- a/src/slic3r/GUI/MainFrame.cpp
+++ b/src/slic3r/GUI/MainFrame.cpp
@@ -525,7 +525,13 @@ void MainFrame::init_tabpanel()
     m_tabpanel->Hide();
     m_settings_dialog.set_tabpanel(m_tabpanel);
 
-    m_tabpanel->Bind(wxEVT_NOTEBOOK_PAGE_CHANGED, [this](wxEvent&) {
+    m_tabpanel->Bind(wxEVT_NOTEBOOK_PAGE_CHANGED, [this](wxBookCtrlEvent& e) {
+#if ENABLE_VALIDATE_CUSTOM_GCODE
+        Tab* old_tab = dynamic_cast<Tab*>(m_tabpanel->GetPage(e.GetOldSelection()));
+        if (old_tab)
+            old_tab->validate_custom_gcodes();
+#endif // ENABLE_VALIDATE_CUSTOM_GCODE
+
         wxWindow* panel = m_tabpanel->GetCurrentPage();
         Tab* tab = dynamic_cast<Tab*>(panel);
 
@@ -544,19 +550,6 @@ void MainFrame::init_tabpanel()
             select_tab(size_t(0)); // select Plater
     });
 
-#if ENABLE_VALIDATE_CUSTOM_GCODE
-    m_tabpanel->Bind(wxEVT_NOTEBOOK_PAGE_CHANGING, [this](wxBookCtrlEvent& evt) {
-        wxWindow* panel = m_tabpanel->GetCurrentPage();
-        if (panel != nullptr) {
-            Tab* tab = dynamic_cast<Tab*>(panel);
-            if (tab != nullptr)
-                tab->validate_custom_gcodes();
-//            if (tab != nullptr && !tab->validate_custom_gcodes())
-//                evt.Veto();
-        }
-        });
-#endif // ENABLE_VALIDATE_CUSTOM_GCODE
-
     m_plater = new Plater(this, this);
     m_plater->Hide();
 
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 74b54478e7..11c4875ebd 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -1738,7 +1738,7 @@ bool Tab::validate_custom_gcode(const wxString& title, const std::string& gcode)
 }
 
 static void validate_custom_gcode_cb(Tab* tab, ConfigOptionsGroupShp opt_group, const t_config_option_key& opt_key, const boost::any& value) {
-    Tab::validate_custom_gcode(opt_group->title, boost::any_cast<std::string>(value));
+    tab->validate_custom_gcodes_was_shown = !Tab::validate_custom_gcode(opt_group->title, boost::any_cast<std::string>(value));
     tab->update_dirty();
     tab->on_value_change(opt_key, value);
 }
@@ -3837,27 +3837,18 @@ bool Tab::validate_custom_gcodes()
     if (m_active_page->title() != L("Custom G-code"))
         return true;
 
+    // When we switch Settings tab after editing of the custom g-code, then warning message could ba already shown after KillFocus event
+    // and then it's no need to show it again
+    if (validate_custom_gcodes_was_shown) {
+        validate_custom_gcodes_was_shown = false;
+        return true;
+    }
+
     bool valid = true;
     for (auto opt_group : m_active_page->m_optgroups) {
         assert(opt_group->opt_map().size() == 1);
         std::string key = opt_group->opt_map().begin()->first;
-        std::string value = boost::any_cast<std::string>(opt_group->get_value(key));
-        std::string config_value = m_type == Preset::TYPE_FILAMENT ? m_config->opt_string(key, 0u) : m_config->opt_string(key);
-        valid &= validate_custom_gcode(opt_group->title, value);
-        Field* field = opt_group->get_field(key);
-        TextCtrl* text_ctrl = dynamic_cast<TextCtrl*>(field);
-        if (text_ctrl != nullptr && text_ctrl->m_on_change != nullptr && !text_ctrl->m_disable_change_event) {
-            Slic3r::GUI::t_change callback = opt_group->m_on_change;
-            // temporary disable the opt_group->m_on_change callback to avoid multiple validations
-            opt_group->m_on_change = nullptr;
-            text_ctrl->m_on_change(key, value);
-            // restore the opt_group->m_on_change callback
-            opt_group->m_on_change = callback;
-
-            update_dirty();
-            on_value_change(key, value);
-        }
-
+        valid &= validate_custom_gcode(opt_group->title, boost::any_cast<std::string>(opt_group->get_value(key)));
         if (!valid)
             break;
     }
diff --git a/src/slic3r/GUI/Tab.hpp b/src/slic3r/GUI/Tab.hpp
index fcbe27eb7f..8cbc6585a7 100644
--- a/src/slic3r/GUI/Tab.hpp
+++ b/src/slic3r/GUI/Tab.hpp
@@ -351,6 +351,7 @@ public:
 #if ENABLE_VALIDATE_CUSTOM_GCODE
 	static bool validate_custom_gcode(const wxString& title, const std::string& gcode);
 	bool        validate_custom_gcodes();
+    bool        validate_custom_gcodes_was_shown { false };
 #endif // ENABLE_VALIDATE_CUSTOM_GCODE
 
 protected: