diff --git a/dune/tectonic/nicefunction.hh b/dune/tectonic/nicefunction.hh
index 015bb5025e61fadb54e02c761a442ba4a3c87dec..2bb5763e33e2224272927b6c0686a4dd65925d34 100644
--- a/dune/tectonic/nicefunction.hh
+++ b/dune/tectonic/nicefunction.hh
@@ -45,7 +45,7 @@ class RuinaFunction : public NiceFunction {
     If mu and sigma_n denote the coefficient of friction and the
     normal stress, respectively, this function is given by
 
-    1/eta sigma_n h(max(eta id, rho)) + a rho + mu
+    1/eta sigma_n r(max(eta id, rho)) + a rho + mu
 
     with the constants a and b from Ruina's model and