diff --git a/cpp/particles/p2p/p2p_ghost_collisions.hpp b/cpp/particles/p2p/p2p_ghost_collisions.hpp
index da7efac13b75c38c080dab7015e910ca10119d8e..166ac5fc1f45d363b6e908d4dd1121b985fd69e0 100644
--- a/cpp/particles/p2p/p2p_ghost_collisions.hpp
+++ b/cpp/particles/p2p/p2p_ghost_collisions.hpp
@@ -55,6 +55,7 @@ class p2p_ghost_collisions
         // description for disks:
         double disk_width;
         bool isActive;
+   protected:        
         void add_colliding_pair(partsize_t idx_part1, partsize_t idx_part2)
         {
             // store colliding particle ids in order, to be able to identify pairs more easily
@@ -69,7 +70,6 @@ class p2p_ghost_collisions
             this->collision_pairs_local.push_back(idx_part_small);
             this->collision_pairs_local.push_back(idx_part_big);
         }
-    protected:
         bool synchronisation;
         std::vector <partsize_t> collision_pairs_local;
         std::vector <partsize_t> collision_pairs_global;