diff --git a/src/slic3r/GUI/Preferences.cpp b/src/slic3r/GUI/Preferences.cpp
index 2197390028..4cc5e58d3a 100644
--- a/src/slic3r/GUI/Preferences.cpp
+++ b/src/slic3r/GUI/Preferences.cpp
@@ -135,13 +135,13 @@ void PreferencesDialog::show(const std::string& highlight_opt_key /*= std::strin
 		downloader->set_path_name(app_config->get("url_downloader_dest"));
 		downloader->allow(!app_config->has("downloader_url_registered") || app_config->get_bool("downloader_url_registered"));
 
-		for (const std::string& opt_key : {"suppress_hyperlinks", "downloader_url_registered", "show_login_button"})
+		for (const std::string opt_key : {"suppress_hyperlinks", "downloader_url_registered", "show_login_button"})
 			m_optgroup_other->set_value(opt_key, app_config->get_bool(opt_key));
 		// by default "Log in" button is visible
 		if (!app_config->has("show_login_button"))
 			m_optgroup_other->set_value("show_login_button", true);
 
-		for (const std::string& opt_key : { "default_action_on_close_application"
+		for (const std::string opt_key : { "default_action_on_close_application"
 										   ,"default_action_on_new_project"
 										   ,"default_action_on_select_preset" })
 			m_optgroup_general->set_value(opt_key, app_config->get(opt_key) == "none");