diff --git a/libs/ardour/rc_configuration.cc b/libs/ardour/rc_configuration.cc
index 7c8f7f3f86..ecc6fefacc 100644
--- a/libs/ardour/rc_configuration.cc
+++ b/libs/ardour/rc_configuration.cc
@@ -239,8 +239,10 @@ RCConfiguration::get_variables (std::string const & node_name) const
 
 #undef  CONFIG_VARIABLE
 #undef  CONFIG_VARIABLE_SPECIAL
+/* due to special case of PBD::ConfigVariable<std::string> we cannot use PBD::to_string<type> (value),
+ * but have to construct a ConfigVariable */
 #define CONFIG_VARIABLE(type,var,Name,value) \
-	var.add_to_node (*node);
+	var.add_to_node_if_modified (*node, ConfigVariable<type> (Name, value).get_as_string ());
 #define CONFIG_VARIABLE_SPECIAL(type,var,Name,value,mutator) \
 	var.add_to_node (*node);
 #include "ardour/rc_configuration_vars.inc.h"
diff --git a/libs/pbd/configuration_variable.cc b/libs/pbd/configuration_variable.cc
index 60d7de2a6f..549dd757fe 100644
--- a/libs/pbd/configuration_variable.cc
+++ b/libs/pbd/configuration_variable.cc
@@ -43,6 +43,21 @@ ConfigVariableBase::add_to_node (XMLNode& node) const
 	node.add_child_nocopy (*child);
 }
 
+void
+ConfigVariableBase::add_to_node_if_modified (XMLNode& node, std::string const& dflt) const
+{
+	const std::string v = get_as_string ();
+	if (v == dflt) {
+		DEBUG_TRACE (DEBUG::Configuration, string_compose ("Config variable '%1' used default, not saved\n", _name));
+		return;
+	}
+	DEBUG_TRACE (DEBUG::Configuration, string_compose ("Config variable '%1' stored as [%2]\n", _name, v));
+	XMLNode* child = new XMLNode ("Option");
+	child->set_property ("name", _name);
+	child->set_property ("value", v);
+	node.add_child_nocopy (*child);
+}
+
 bool
 ConfigVariableBase::set_from_node (XMLNode const & node)
 {
diff --git a/libs/pbd/pbd/configuration_variable.h b/libs/pbd/pbd/configuration_variable.h
index 28c1099aa2..79b7b893c8 100644
--- a/libs/pbd/pbd/configuration_variable.h
+++ b/libs/pbd/pbd/configuration_variable.h
@@ -34,6 +34,7 @@ class LIBPBD_API ConfigVariableBase {
 
 	std::string name () const { return _name; }
 	void add_to_node (XMLNode&) const;
+	void add_to_node_if_modified (XMLNode&, std::string const&) const;
 	bool set_from_node (XMLNode const &);
 
 	virtual std::string get_as_string () const = 0;