diff --git a/src/state/ageinglawstateupdater.cc b/src/state/ageinglawstateupdater.cc
index 1461e29907e0ac65f6f3a90100a5416088686470..ec69fac30fa339520e8ec6b6c719860d43c22399 100644
--- a/src/state/ageinglawstateupdater.cc
+++ b/src/state/ageinglawstateupdater.cc
@@ -2,8 +2,8 @@
 
 template <class ScalarVector, class Vector>
 AgeingLawStateUpdater<ScalarVector, Vector>::AgeingLawStateUpdater(
-    ScalarVector _alpha_initial, Dune::BitSetVector<1> const &_nodes, double _L,
-    double _V0)
+    ScalarVector const &_alpha_initial, Dune::BitSetVector<1> const &_nodes,
+    double _L, double _V0)
     : alpha(_alpha_initial), nodes(_nodes), L(_L), V0(_V0) {}
 
 template <class ScalarVector, class Vector>
diff --git a/src/state/ageinglawstateupdater.hh b/src/state/ageinglawstateupdater.hh
index 5b6fec71f1cbb3411a20f7dd4ca1d867d7d87bb5..c8ae85c7e348a4598d340f93f731289c386be328 100644
--- a/src/state/ageinglawstateupdater.hh
+++ b/src/state/ageinglawstateupdater.hh
@@ -7,7 +7,7 @@
 template <class ScalarVector, class Vector>
 class AgeingLawStateUpdater : public StateUpdater<ScalarVector, Vector> {
 public:
-  AgeingLawStateUpdater(ScalarVector _alpha_initial,
+  AgeingLawStateUpdater(ScalarVector const &_alpha_initial,
                         Dune::BitSetVector<1> const &_nodes, double _L,
                         double _V0);
 
diff --git a/src/state/sliplawstateupdater.cc b/src/state/sliplawstateupdater.cc
index 5397c1d2e4845483dc25843eff816c5978f4b092..2b3e643c39051425959e014e598666a07118700b 100644
--- a/src/state/sliplawstateupdater.cc
+++ b/src/state/sliplawstateupdater.cc
@@ -2,8 +2,8 @@
 
 template <class ScalarVector, class Vector>
 SlipLawStateUpdater<ScalarVector, Vector>::SlipLawStateUpdater(
-    ScalarVector _alpha_initial, Dune::BitSetVector<1> const &_nodes, double _L,
-    double _V0)
+    ScalarVector const &_alpha_initial, Dune::BitSetVector<1> const &_nodes,
+    double _L, double _V0)
     : alpha(_alpha_initial), nodes(_nodes), L(_L), V0(_V0) {}
 
 template <class ScalarVector, class Vector>
diff --git a/src/state/sliplawstateupdater.hh b/src/state/sliplawstateupdater.hh
index f527c1c40ddd16714a3b79c03a3be59dfde1a1b1..e12e004ca266f9cb386f34033f46b8930abe41d6 100644
--- a/src/state/sliplawstateupdater.hh
+++ b/src/state/sliplawstateupdater.hh
@@ -7,7 +7,7 @@
 template <class ScalarVector, class Vector>
 class SlipLawStateUpdater : public StateUpdater<ScalarVector, Vector> {
 public:
-  SlipLawStateUpdater(ScalarVector _alpha_initial,
+  SlipLawStateUpdater(ScalarVector const &_alpha_initial,
                       Dune::BitSetVector<1> const &_nodes, double _L,
                       double _V0);