diff --git a/dune/tectonic/nicefunction.hh b/dune/tectonic/nicefunction.hh
index 7acf4bec3acc4652c6b471d1b9eddb71815a3d9c..10b7417d64510756337e924ac099eb6a9a99b8b6 100644
--- a/dune/tectonic/nicefunction.hh
+++ b/dune/tectonic/nicefunction.hh
@@ -51,6 +51,15 @@ class RuinaFunction : public NiceFunction {
                                                  // logarithmic
         rho(std::exp(-K / a)) {}
 
+  double virtual evaluate(double x) const {
+    double const arg = x / h * eta;
+    if (arg <= rho)
+      return 0;
+
+    return coefficientProduct *
+           (+a * arg * (std::log(arg) - 1) + K * arg + a * rho);
+  }
+
   double virtual leftDifferential(double x) const {
     double const arg = x / h * eta;
     if (arg <= rho)