--- a/CREDITS	Sat Apr 08 21:43:48 2017 +0200
+++ b/CREDITS	Sat Apr 08 21:48:25 2017 +0200
@@ -81,6 +81,7 @@
      http://www.freesound.org/people/uair01/sounds/65291/
 - Air mine impact sound by Wuzzy (WTFPL), based on
      http://www.freesound.org/people/batchku/sounds/10479/
+- Rubber duck sounds are in the Public Domain.
 - Countdown sounds by Wuzzy (WTFPL)
 - Laser Sight sound originally from drzhn (CC-0), remixed from
      https://www.freesound.org/people/drzhnn/sounds/199938/