diff --git a/gtk2_ardour/keyboard.cc b/gtk2_ardour/keyboard.cc
index bdce6badda..96c73f63d4 100644
--- a/gtk2_ardour/keyboard.cc
+++ b/gtk2_ardour/keyboard.cc
@@ -242,6 +242,9 @@ ArdourKeyboard::set_state (const XMLNode& node, int version)
 	return Keyboard::set_state (node, version);
 }
 
+/* Snap and snap delta modifiers may contain each other, so we use the 
+ * following two methods to sort that out:
+ */
 bool
 ArdourKeyboard::indicates_snap (guint state)
 {
diff --git a/gtk2_ardour/keyboard.h b/gtk2_ardour/keyboard.h
index b163bfaa37..9ca60950bb 100644
--- a/gtk2_ardour/keyboard.h
+++ b/gtk2_ardour/keyboard.h
@@ -41,7 +41,14 @@ class ArdourKeyboard : public Gtkmm2ext::Keyboard
 
 	ARDOUR_UI& ui;
 
+	/** @param state The button state from a GdkEvent.
+	 *  @return true if the modifier state indicates snap modifier
+	 */
 	static bool indicates_snap (guint state);
+
+	/** @param state The button state from a GdkEvent.
+	 *  @return true if the modifier state indicates snap delta
+	 */
 	static bool indicates_snap_delta (guint state);
 
 	static void set_constraint_modifier (guint);