diff --git a/src/libslic3r/PresetBundle.cpp b/src/libslic3r/PresetBundle.cpp
index 7c0f25f8a..9c1d3718f 100644
--- a/src/libslic3r/PresetBundle.cpp
+++ b/src/libslic3r/PresetBundle.cpp
@@ -3805,9 +3805,14 @@ void PresetBundle::update_multi_material_filament_presets(size_t to_delete_filam
 
     // Now verify if flush_volumes_matrix has proper size (it is used to deduce number of extruders in wipe tower generator):
     std::vector<double> old_matrix = this->project_config.option<ConfigOptionFloats>("flush_volumes_matrix")->values;
-
+    size_t old_nozzle_nums = this->project_config.option<ConfigOptionFloats>("flush_multiplier")->values.size();
+    size_t old_number_of_filaments = size_t(sqrt(old_matrix.size() / old_nozzle_nums) + EPSILON);
     size_t nozzle_nums = get_printer_extruder_count();
-    size_t old_number_of_filaments = size_t(sqrt(old_matrix.size() / nozzle_nums) + EPSILON);
+    if (old_nozzle_nums != nozzle_nums) {
+        std::vector<double>& f_multiplier = this->project_config.option<ConfigOptionFloats>("flush_multiplier")->values;
+        f_multiplier.resize(nozzle_nums, 1.f);
+    }
+
     if (num_filaments != old_number_of_filaments) {
         // First verify if purging volumes presets for each extruder matches number of extruders
         std::vector<double>& filaments = this->project_config.option<ConfigOptionFloats>("flush_volumes_vector")->values;
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 8b7a391e1..6356a5b81 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -1120,11 +1120,9 @@ Sidebar::Sidebar(Plater *parent)
             ConfigOptionFloats *flush_multi_opt = project_config.option<ConfigOptionFloats>("flush_multiplier");
             if (flush_multi_opt)
                 flush_multiplier = cast<float>(flush_multi_opt->values);
-            else {
-                for (size_t nozzle_id = 0; nozzle_id < nozzle_nums; ++nozzle_id) {
-                    flush_multiplier.push_back(1.f);
-                }
-            }
+
+            flush_multiplier.resize(nozzle_nums, 1.0f);
+
             WipingDialog dlg(parent, cast<float>(init_matrix), cast<float>(init_extruders), extruder_colours, extra_flush_volumes, flush_multiplier, nozzle_nums);
             if (dlg.ShowModal() == wxID_OK) {
                 std::vector<float> matrix = dlg.get_matrix();