diff --git a/src/GRANULAR/gran_sub_mod_damping.cpp b/src/GRANULAR/gran_sub_mod_damping.cpp
index 1745f6addf..09ac4bf962 100644
--- a/src/GRANULAR/gran_sub_mod_damping.cpp
+++ b/src/GRANULAR/gran_sub_mod_damping.cpp
@@ -159,6 +159,8 @@ GranSubModDampingCoeffRestitution::GranSubModDampingCoeffRestitution(GranularMod
   allow_cohesion = 0;
 }
 
+/* ---------------------------------------------------------------------- */
+
 void GranSubModDampingCoeffRestitution::init()
 {
   // Calculate prefactor, assume Hertzian as default
@@ -172,6 +174,8 @@ void GranSubModDampingCoeffRestitution::init()
   }
 }
 
+/* ---------------------------------------------------------------------- */
+
 double GranSubModDampingCoeffRestitution::calculate_forces()
 {
   // in case argument <= 0 due to precision issues