diff --git a/src/simulation.cpp b/src/simulation.cpp
index 62f0bd2d2..00d9d391d 100644
--- a/src/simulation.cpp
+++ b/src/simulation.cpp
@@ -541,9 +541,7 @@ void process_collision_events()
         // If next level is rotated, apply rotation matrix
         const auto& m {model::cells[p->coord_[j].cell]->rotation_};
         const auto& u {p->coord_[j].u};
-        p->coord_[j + 1].u.x = m[3]*u.x + m[4]*u.y + m[5]*u.z;
-        p->coord_[j + 1].u.y = m[6]*u.x + m[7]*u.y + m[8]*u.z;
-        p->coord_[j + 1].u.z = m[9]*u.x + m[10]*u.y + m[11]*u.z;
+        p->coord_[j + 1].u = u.rotate(m);
       } else {
         // Otherwise, copy this level's direction
         p->coord_[j+1].u = p->coord_[j].u;