diff --git a/src/PenningTrap.cpp b/src/PenningTrap.cpp
index 95a03c4..8f7996f 100644
--- a/src/PenningTrap.cpp
+++ b/src/PenningTrap.cpp
@@ -158,7 +158,7 @@ void PenningTrap::reinitialize(double f, double omega_V, double t)
 
     for (size_t i = 0; i < this->particles.size(); i++) {
         p = &this->particles[i];
-        p->v_vec = vec3().randn() * .1 * this->d;
+        p->r_vec = vec3().randn() * .1 * this->d;
         p->v_vec = vec3().randn() * .1 * this->d;
     }
 }
@@ -172,6 +172,7 @@ void PenningTrap::evolve_RK4(double dt, bool particle_interaction)
 {
     Particle *p;
 
+    // Keep original particles
     std::vector<Particle> original_particles = this->particles;
     std::vector<Particle> tmp_particles = this->particles;