diff --git a/dune/tectonic/io/hdf5-writer.hh b/dune/tectonic/io/hdf5-writer.hh
index 6a89f7233a04beb29feb7e7f073fc05bb153ed10..00cc66ba3a53d3cf925c000c254db781419b21c6 100644
--- a/dune/tectonic/io/hdf5-writer.hh
+++ b/dune/tectonic/io/hdf5-writer.hh
@@ -37,7 +37,7 @@ class HDF5Writer {
     }
 
     template <class ContactNetwork, class Friction>
-    void reportSolution(const ProgramState& programState, const ContactNetwork& contactNetwork, Friction& friction) {
+    void reportSolution(const ProgramState& programState, const ContactNetwork& contactNetwork, const Friction& friction) {
 
         timeWriter_.write(programState);