diff --git a/src/libslic3r/Preset.cpp b/src/libslic3r/Preset.cpp
index 8ee923cac7..e4bad2c723 100644
--- a/src/libslic3r/Preset.cpp
+++ b/src/libslic3r/Preset.cpp
@@ -351,7 +351,7 @@ void Preset::normalize(DynamicPrintConfig &config)
                 static_cast<ConfigOptionVectorBase*>(opt)->resize(n, defaults.option(key));
         }
         // The following keys are mandatory for the UI, but they are not part of FullPrintConfig, therefore they are handled separately.
-        for (const std::string key : { "filament_settings_id" }) {
+        for (const std::string &key : { "filament_settings_id" }) {
             auto *opt = config.option(key, false);
             assert(opt == nullptr || opt->type() == coStrings);
             if (opt != nullptr && opt->type() == coStrings)
diff --git a/src/libslic3r/PresetBundle.cpp b/src/libslic3r/PresetBundle.cpp
index 2e88552926..594cf0f3da 100644
--- a/src/libslic3r/PresetBundle.cpp
+++ b/src/libslic3r/PresetBundle.cpp
@@ -2173,7 +2173,8 @@ DynamicPrintConfig PresetBundle::full_fff_config(bool apply_extruder, std::vecto
     // BBS
     size_t  num_filaments = this->filament_presets.size();
 
-    if (filament_maps.empty()) {
+    //in some middle state, they may be different
+    if (filament_maps.size() != num_filaments) {
         filament_maps.resize(num_filaments, 1);
     }