diff --git a/libs/pbd/pbd/controllable.h b/libs/pbd/pbd/controllable.h
index 2e114e233e..ca4572fe69 100644
--- a/libs/pbd/pbd/controllable.h
+++ b/libs/pbd/pbd/controllable.h
@@ -133,7 +133,11 @@ public:
 
 	/** Get and Set `interface' value  (typically, fraction of knob travel) */
 	virtual float get_interface(bool rotary=false) const { return (internal_to_interface(get_value(), rotary)); }
-	virtual void set_interface (float fraction, bool rotary=false) { fraction = min( max(0.0f, fraction), 1.0f);  set_value(interface_to_internal(fraction, rotary), NoGroup); }
+
+	virtual void set_interface (float fraction, bool rotary=false, GroupControlDisposition gcd = NoGroup) {
+		fraction = std::min (std::max (0.0f, fraction), 1.0f);
+		set_value (interface_to_internal (fraction, rotary), gcd);
+	}
 
 	virtual std::string get_user_string() const { return std::string(); }