diff --git a/src/libslic3r/AppConfig.cpp b/src/libslic3r/AppConfig.cpp
index aa82a5a54..bcfd5b3ef 100644
--- a/src/libslic3r/AppConfig.cpp
+++ b/src/libslic3r/AppConfig.cpp
@@ -462,8 +462,11 @@ std::string AppConfig::load()
                         for(auto& element: iter.value()) {
                             if (idx == 0)
                                 m_storage[it.key()]["filament"] = element;
-                            else
-                                m_storage[it.key()]["filament_" + std::to_string(idx)] = element;
+                            else {
+                                auto n = std::to_string(idx);
+                                if (n.length() == 1) n = "0" + n;
+                                m_storage[it.key()]["filament_" + n] = element;
+                            }
                             idx++;
                         }
                     } else {
diff --git a/src/libslic3r/PresetBundle.cpp b/src/libslic3r/PresetBundle.cpp
index 2bbee66ef..b67af2d0b 100644
--- a/src/libslic3r/PresetBundle.cpp
+++ b/src/libslic3r/PresetBundle.cpp
@@ -1293,7 +1293,7 @@ void PresetBundle::load_selections(AppConfig &config, const PresetPreferences& p
     this->filament_presets = { filaments.get_selected_preset_name() };
     for (unsigned int i = 1; i < 1000; ++ i) {
         char name[64];
-        sprintf(name, "filament_%u", i);
+        sprintf(name, "filament_%02u", i);
         if (! config.has("presets", name))
             break;
         this->filament_presets.emplace_back(remove_ini_suffix(config.get("presets", name)));
@@ -1371,7 +1371,7 @@ void PresetBundle::export_selections(AppConfig &config)
     config.set("presets", PRESET_FILAMENT_NAME,     filament_presets.front());
     for (unsigned i = 1; i < filament_presets.size(); ++i) {
         char name[64];
-        sprintf(name, "filament_%u", i);
+        sprintf(name, "filament_%02u", i);
         config.set("presets", name, filament_presets[i]);
     }
     CNumericLocalesSetter locales_setter;