diff --git a/src/fraggle/fraggle_regime.f90 b/src/fraggle/fraggle_regime.f90
index 2888d234f..a20b08d29 100644
--- a/src/fraggle/fraggle_regime.f90
+++ b/src/fraggle/fraggle_regime.f90
@@ -60,9 +60,6 @@ module subroutine fraggle_regime_colliders(self, frag, system, param)
          ! Convert quantities back to the system units and save them into the fragment system
          frag%mass_dist(:) = (frag%mass_dist(:) / param%MU2KG) 
          frag%Qloss = frag%Qloss * (param%TU2S / param%DU2M)**2 / param%MU2KG
-         frag%mtot = sum(colliders%mass(:))
-         frag%xbcom(:) = (colliders%mass(1) * colliders%xb(:,1) + colliders%mass(2) * colliders%xb(:,2)) / frag%mtot 
-         frag%vbcom(:) = (colliders%mass(1) * colliders%vb(:,1) + colliders%mass(2) * colliders%vb(:,2)) / frag%mtot
 
          call fraggle_io_log_regime(colliders, frag)
       end associate
diff --git a/src/symba/symba_collision.f90 b/src/symba/symba_collision.f90
index bc9afd880..11b3b874c 100644
--- a/src/symba/symba_collision.f90
+++ b/src/symba/symba_collision.f90
@@ -888,6 +888,9 @@ module subroutine symba_collision_resolve_fragmentations(self, system, param)
                   if ((.not. lgoodcollision) .or. any(pl%status(idx_parent(:)) /= COLLISION)) cycle
 
                   call colliders%regime(frag, system, param)
+                  frag%mtot = sum(colliders%mass(:))
+                  frag%xbcom(:) = (colliders%mass(1) * colliders%xb(:,1) + colliders%mass(2) * colliders%xb(:,2)) / frag%mtot 
+                  frag%vbcom(:) = (colliders%mass(1) * colliders%vb(:,1) + colliders%mass(2) * colliders%vb(:,2)) / frag%mtot
    
                   select case (frag%regime)
                   case (COLLRESOLVE_REGIME_DISRUPTION, COLLRESOLVE_REGIME_SUPERCATASTROPHIC)
@@ -941,6 +944,9 @@ module subroutine symba_collision_resolve_mergers(self, system, param)
                   if (any(pl%status(idx_parent(:)) /= COLLISION)) cycle ! One of these two bodies has already been resolved
  
                   frag%regime = COLLRESOLVE_REGIME_MERGE
+                  frag%mtot = sum(colliders%mass(:))
+                  frag%xbcom(:) = (colliders%mass(1) * colliders%xb(:,1) + colliders%mass(2) * colliders%xb(:,2)) / frag%mtot 
+                  frag%vbcom(:) = (colliders%mass(1) * colliders%vb(:,1) + colliders%mass(2) * colliders%vb(:,2)) / frag%mtot
                   plplcollision_list%status(i) = symba_collision_casemerge(system, param, colliders, frag)
                end do
             end select