diff --git a/src/atom_vec_hybrid.cpp b/src/atom_vec_hybrid.cpp
index 88d21e85a1..4149a362e6 100644
--- a/src/atom_vec_hybrid.cpp
+++ b/src/atom_vec_hybrid.cpp
@@ -223,6 +223,7 @@ void AtomVecHybrid::process_args(int narg, char **arg)
 
   // set bonus_flag if any substyle has bonus data
   // set nstyles_bonus & styles_bonus
+  // sum two sizes over contributions from each substyle with bonus data.
 
   nstyles_bonus = 0;
   for (int k = 0; k < nstyles; k++)
@@ -232,6 +233,8 @@ void AtomVecHybrid::process_args(int narg, char **arg)
     bonus_flag = 1;
     styles_bonus = new AtomVec*[nstyles_bonus];
     nstyles_bonus = 0;
+    size_forward_bonus = 0;
+    size_border_bonus = 0;
     for (int k = 0; k < nstyles; k++) {
       if (styles[k]->bonus_flag) {
         styles_bonus[nstyles_bonus++] = styles[k];