diff --git a/src/libslic3r/PlaceholderParser.hpp b/src/libslic3r/PlaceholderParser.hpp
index ae6ef8f02..6157ffe3c 100644
--- a/src/libslic3r/PlaceholderParser.hpp
+++ b/src/libslic3r/PlaceholderParser.hpp
@@ -24,6 +24,7 @@ public:
 
     PlaceholderParser(const DynamicConfig *external_config = nullptr);
     
+    void clear_config() { m_config.clear(); }
     // Return a list of keys, which should be changed in m_config from rhs.
     // This contains keys, which are found in rhs, but not in m_config.
     std::vector<std::string> config_diff(const DynamicPrintConfig &rhs);
diff --git a/src/libslic3r/PrintApply.cpp b/src/libslic3r/PrintApply.cpp
index 0e252ac6f..50583960f 100644
--- a/src/libslic3r/PrintApply.cpp
+++ b/src/libslic3r/PrintApply.cpp
@@ -216,22 +216,25 @@ static t_config_option_keys print_config_diffs(
         const ConfigOption *opt_new_filament = std::binary_search(extruder_retract_keys.begin(), extruder_retract_keys.end(), opt_key) ? new_full_config.option(filament_prefix + opt_key) : nullptr;
         if (opt_new_filament != nullptr && ! opt_new_filament->is_nil()) {
             // An extruder retract override is available at some of the filament presets.
-            if (*opt_old != *opt_new || opt_new->overriden_by(opt_new_filament)) {
+            bool overriden = opt_new->overriden_by(opt_new_filament);
+            if (overriden || *opt_old != *opt_new) {
                 auto opt_copy = opt_new->clone();
                 opt_copy->apply_override(opt_new_filament);
-                if (*opt_old == *opt_copy)
-                    delete opt_copy;
-                else {
-                    filament_overrides.set_key_value(opt_key, opt_copy);
+                bool changed = *opt_old != *opt_copy;
+                if (changed)
                     print_diff.emplace_back(opt_key);
-                }
+                if (changed || overriden) {
+                    // filament_overrides will be applied to the placeholder parser, which layers these parameters over full_print_config.
+                    filament_overrides.set_key_value(opt_key, opt_copy);
+                } else
+                    delete opt_copy;
             }
         } else if (*opt_new != *opt_old)
             print_diff.emplace_back(opt_key);
     }
 
     return print_diff;
- }
+}
 
 // Prepare for storing of the full print config into new_full_config to be exported into the G-code and to be used by the PlaceholderParser.
 static t_config_option_keys full_print_config_diffs(const DynamicPrintConfig &current_full_config, const DynamicPrintConfig &new_full_config)
@@ -928,6 +931,7 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
     bool   num_extruders_changed = false;
     if (! full_config_diff.empty()) {
         update_apply_status(this->invalidate_step(psGCodeExport));
+        m_placeholder_parser.clear_config();
         // Set the profile aliases for the PrintBase::output_filename()
 		m_placeholder_parser.set("print_preset",              new_full_config.option("print_settings_id")->clone());
 		m_placeholder_parser.set("filament_preset",           new_full_config.option("filament_settings_id")->clone());
@@ -939,6 +943,8 @@ Print::ApplyStatus Print::apply(const Model &model, DynamicPrintConfig new_full_
 	    // It is also safe to change m_config now after this->invalidate_state_by_config_options() call.
 	    m_config.apply_only(new_full_config, print_diff, true);
 	    //FIXME use move semantics once ConfigBase supports it.
+        // Some filament_overrides may contain values different from new_full_config, but equal to m_config.
+        // As long as these config options don't reallocate memory when copying, we are safe overriding a value, which is in use by a worker thread.
 	    m_config.apply(filament_overrides);
 	    // Handle changes to object config defaults
 	    m_default_object_config.apply_only(new_full_config, object_diff, true);