diff --git a/dune/tectonic/globalruinanonlinearity.hh b/dune/tectonic/globalruinanonlinearity.hh
index 2ff49ef05284dd1d2efbc98571aafdbe5c0e1471..2634563dbaeb22471456852d48b9b24471d19c37 100644
--- a/dune/tectonic/globalruinanonlinearity.hh
+++ b/dune/tectonic/globalruinanonlinearity.hh
@@ -39,6 +39,7 @@ class GlobalRuinaNonlinearity
     if ((*nodalIntegrals)[i][0] == 0)
       return trivialNonlinearity;
 
+    // TODO: cache functions
     shared_ptr<NiceFunction const> const func(
         new RuinaFunction((*nodalIntegrals)[i][0], (*a)[i][0], (*mu)[i][0],
                           (*eta)[i][0], (*normalStress)[i][0]));