diff --git a/dune/tectonic/data-structures/friction/globalfriction.hh b/dune/tectonic/data-structures/friction/globalfriction.hh
index e8796c30ca68afe0096da03b472618dd7a2641f7..25de684598883f9e4c4d0e949d0cfca0ca94a019 100644
--- a/dune/tectonic/data-structures/friction/globalfriction.hh
+++ b/dune/tectonic/data-structures/friction/globalfriction.hh
@@ -78,8 +78,9 @@ class GlobalFriction {
 
   ScalarVector coefficientOfFriction(Vector const &x) const {
     ScalarVector ret(x.size());
-    for (size_t i = 0; i < x.size(); ++i)
+    for (size_t i = 0; i < x.size(); ++i) {
       ret[i] = restriction(i).coefficientOfFriction(x[i]);
+    }
     return ret;
   }