diff --git a/partitioned-heat-conduction/fenics/utils/ButcherTableaux.py b/partitioned-heat-conduction/fenics/utils/ButcherTableaux.py
index 172c687be..07ae830c5 100644
--- a/partitioned-heat-conduction/fenics/utils/ButcherTableaux.py
+++ b/partitioned-heat-conduction/fenics/utils/ButcherTableaux.py
@@ -3,6 +3,8 @@
 from numpy import vander
 
 
+# This file originates from https://github.com/firedrakeproject/Irksome/blob/master/irksome/ButcherTableaux.py, please add a corresponding note or delete this file and make irksome a dependency of this code.
+
 class ButcherTableau(object):
     """Top-level class representing a Butcher tableau encoding
        a Runge-Kutta method.  It has members