diff --git a/libs/ardour/ardour/configuration_variable.h b/libs/ardour/ardour/configuration_variable.h
index ec02a86fc5..ec954e8d9c 100644
--- a/libs/ardour/ardour/configuration_variable.h
+++ b/libs/ardour/ardour/configuration_variable.h
@@ -77,7 +77,7 @@ class ConfigVariable : public ConfigVariableBase
 		return true;
 	}
 
-	void set_from_string (std::string const & s) {
+	virtual void set_from_string (std::string const & s) {
 		std::stringstream ss;
 		ss << s;
 		ss >> value;
@@ -140,6 +140,14 @@ class ConfigVariableWithMutation : public ConfigVariable<T>
 		return false;
 	}
 
+	void set_from_string (std::string const & s) {
+                T v;
+                std::stringstream ss;
+                ss << s;
+		ss >> v;
+                set (v);
+	}
+
   protected:
 	virtual T get_for_save() { return unmutated_value; }
 	T unmutated_value;